Squeak-dev December 2015

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161 discussions

[Unicode][m17n] Where do I find the m17n paper? (Multilingual Squeak)
by H. Hirzel 07 Dec '15

07 Dec '15

Hello Yoshiki Your paper on the design and implementation of the m17n package [1] http://www.is.titech.ac.jp/~ohshima/squeak/squeak-multilingual-e.html is no longer accessible. Where can I get it from these days? Regards Hannes [1] Multilingual Squeak http://wiki.squeak.org/squeak/919

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Reed Solomon Blues
by Robert Withers 07 Dec '15

07 Dec '15

Hi Good morning, I am trying to port java code implementing Reed-Solomon encoding with a GaloisField and polynomial system. I am currently testing the easiest Mode, which is 9 data symbols, 15 code symbols and 3 symbols of error. Theer's 2 nibbles to a byte, so a split and join is needed. This all has to do with iteration where the base indexing changes from 0 to 1. I screwed it up in there somewhere and I am struggling to find teh issue. It looks like a complete code review... Since this is core crypto code, it would be an extra blessing if someone else's eyes were on this code in detail.More tests always help too. Would someone be willing to crawl into the java and squeak code to review, learn and qualify/validate? Also, you would be helping me understand all this polynomial math and where my indexing issue may be. The failure in Squeak is in the GenericGFPoly>>#divide: method. It runs forever and the quotient/remainder never reduces it's degree. So one of teh math operations is broken & failing. You can run the EncodingTests I am including a zip of the Java classes I use. This core Reed-Solomon code was written at Google and released open-source. I wrote a test and they pass, so code is working. The latest Cryptography package in the crypto repo is version 48. Please load that and run the CryptoReedSolomonTest to see the infiniteLoop of the polynomial divide. Let me know if you can help. Thanks, Robert

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Re: [Pharo-dev] Unicode Support
by EuanM 07 Dec '15

07 Dec '15

This a long email. A *lot* of it is encapsulated in the Venn diagram both: http://smalltalk.uk.to/unicode-utf8.html and my Smalltalk in Small Steps blog at: http://smalltalkinsmallsteps.blogspot.co.uk/2015/12/utf-8-for-cuis-pharo-an… My current thinking, and understanding. ============================== 0) a) ASCII and ISO-8859-1 consist of characters encoded in 1 byte. b) UTF-8 can encode all of those characters in 1 byte, but can prefer some of them to be encoded as sequences of multiple bytes. And can encode additional characters as sequences of multiple bytes. 1) Smalltalk has long had multiple String classes. 2) Any UTF16 Unicode codepoint which has a codepoint of 00nn hex is encoded as a UTF-8 codepoint of nn hex. 3) All valid ISO-8859-1 characters have a character code between 20 hex and 7E hex, or between A0 hex and FF hex. https://en.wikipedia.org/wiki/ISO/IEC_8859-1 4) All valid ASCII characters have a character code between 00 hex and 7E hex. https://en.wikipedia.org/wiki/ASCII 5) a) All character codes which are defined within ISO-8859-1 and also defined within ASCII. (i.e. character codes 20 hex to 7E hex) are defined identically in both. b) All printable ASCII characters are defined identically in both ASCII and ISO-8859-1 6) All character codes defined in ASCII (00 hex to 7E hex) are defined identically in Unicode UTF-8. 7) All character codes defined in ISO-8859-1 (20 hex - 7E hex ; A0 hex - FF hex ) are defined identically in UTF-8. 8) => some Unicode codepoints map to both ASCII and ISO-8859-1. all ASCII maps 1:1 to Unicode UTF-8 all ISO-8859-1 maps 1:1 to Unicode UTF-8 9) All ByteStrings elements which are either a valid ISO-8859-1 character or a valid ASCII character are *also* a valid UTF-8 character. 10) ISO-8859-1 characters representing a character with a diacritic, or a two-character ligature, have no ASCII equivalent. In Unicode UTF-8, those character codes which are representing compound glyphs, are called "compatibility codepoints". 11) The preferred Unicode representation of the characters which have compatibility codepoints is as a a short set of codepoints representing the characters which are combined together to form the glyph of the convenience codepoint, as a sequence of bytes representing the component characters. 12) Some concrete examples: A - aka Upper Case A In ASCII, in ISO 8859-1 ASCII A - 41 hex ISO-8859-1 A - 41 hex UTF-8 A - 41 hex BEL (a bell sound, often invoked by a Ctrl-g keyboard chord) In ASCII, not in ISO 8859-1 ASCII : BEL - 07 hex ISO-8859-1 : 07 hex is not a valid character code UTF-8 : BEL - 07 hex £ (GBP currency symbol) In ISO-8859-1, not in ASCII ASCII : A3 hex is not a valid ASCII code UTF-8: £ - A3 hex ISO-8859-1: £ - A3 hex Upper Case C cedilla In ISO-8859-1, not in ASCII, in UTF-8 as a compatibility codepoint *and* a composed set of codepoints ASCII : C7 hex is not a valid ASCII character code ISO-8859-1 : Upper Case C cedilla - C7 hex UTF-8 : Upper Case C cedilla (compatibility codepoint) - C7 hex Unicode preferred Upper Case C cedilla (composed set of codepoints) Upper case C 0043 hex (Upper case C) followed by cedilla 00B8 hex (cedilla) 13) For any valid ASCII string *and* for any valid ISO-8859-1 string, aByteString is completely adequate for editing and display. 14) When sorting any valid ASCII string *or* any valid ISO-8859-1 string, upper and lower case versions of the same character will be treated differently. 15) When sorting any valid ISO-8859-1 string containing letter+diacritic combination glyphs or ligature combination glyphs, the glyphs in combination will treated differently to a "plain" glyph of the character i.e. "C" and "C cedilla" will be treated very differently. "ß" and "fs" will be treated very differently. 16) Different nations have different rules about where diacritic-ed characted and ligature pairs should be placed when in alphabetical order. 17) Some nations even have multiple standards - e.g. surnames beginning either "M superscript-c" or "M superscript-a superscript-c" are treated as beginning equivalently in UK phone directories, but not in other situations. Some practical upshots ================== 1) Cuis and its ISO-8859-1 encoding is *exactly* the same as UTF-8, for any single character it considers valid, or any ByteString it has made up of characters it considers valid. 2) Any ByteString is valid UTF-8 in any of Squeak, Pharo, Cuis or any other Smalltalk with a single byte ByteString following ASCII or ISO-8859-1. 3) Any Smalltalk (or derivative language) using ByteString can immediately consider it's ByteString as valid UTF-8, as long as it also considers the ByteSring as valid ASCII and/or ISO-8859-1. 4) All of those can be successfully exported to any system using UTF-8 (e.g. HTML). 5) To successfully *accept* all UTF-8 we much be able to do either: a) accept UTF-8 strings with composed characters b) convert UTF-8 strings with composed characters into UTF-8 strings that use *only* compatibility codepoints. Class + protocol proposals a Utf8CompatibilityString class. asByteString - ensure only compatibility codepoints are used. Ensure it doews not encode characters above 00FF hex. asIso8859String - ensures only compatibility codepoints are used, and that the characters are each valid ISO 8859-1 asAsciiString - ensures only characters 00hex - 7F hex are used. asUtf8ComposedIso8859String - ensures all compatibility codepoints are expanded into small OrderedCollections of codepoints a Utf8ComposedIso8859String class - will provide sortable and comparable UTF8 strings of all ASCII and ISO 8859-1 strings. Then a Utf8SortableCollection class - a collection of Utf8ComposedIso8859Strings words and phrases. Custom sortBlocks will define the applicable sort order. We can create a collection... a Dictionary, thinking about it, of named, prefabricated sortBlocks. This will work for all UTF8 strings of ISO-8859-1 and ASCII strings. If anyone has better names for the classes, please let me know. If anyone else wants to help - build these, - create SUnit tests for these - write documentation for these Please let me know. n.b. I have had absolutely no experience of Ropes. My own background with this stuff: In the early 90's as a Project Manager implementing office automation systems across a global company, with offices in the Americas, Western, Eastern and Central Europe, (including Slavic and Cyrillic users) nations, Japan and China. The mission-critical application was word-processing. Our offices were spread around the globe, and we needed those offices to successfully exchange documents with their sister offices, and with the customers in each region the offices were in. Unicode was then new, and our platform supplier was the NeXT Corporation, who had been founder members in of the Unicode Consortium in 1990. So far: I've read the latest version of the Unicode Standard (v8.0). This is freely downloadable. I've purchased a paper copy of an earlier release. New releases typically consist additional codespaces (i.e. alphabets). So old copies are useful, as well as cheap. (Paper copies of version 4.0 are available second-hand for < $10 / €10). The typical change with each release is the addition of further codespaces (i.e alphabets (more or less) ), so you don't lose a lot. (I'll be going through my V4.0 just to make sure) Cheers, Euan On 5 December 2015 at 13:08, stepharo <stepharo(a)free.fr> wrote: > Hi EuanM > > Le 4/12/15 12:42, EuanM a écrit : >> >> I'm currently groping my way to seeing how feature-complete our >> Unicode support is. I am doing this to establish what still needs to >> be done to provide full Unicode support. > > > this is great. Thanks for pushing this. I wrote and collected some roadmap > (analyses on different topics) > on the pharo github project feel free to add this one there. >> >> >> This seems to me to be an area where it would be best to write it >> once, and then have the same codebase incorporated into the Smalltalks >> that most share a common ancestry. >> >> I am keen to get: equality-testing for strings; sortability for >> strings which have ligatures and diacritic characters; and correct >> round-tripping of data. > > Go! > My suggestion is > start small > make steady progress > write tests > commit often :) > > Stef > > What is the french phoneBook ordering because this is the first time I hear > about it. > >> >> Call to action: >> ========== >> >> If you have comments on these proposals - such as "but we already have >> that facility" or "the reason we do not have these facilities is >> because they are dog-slow" - please let me know them. >> >> If you would like to help out, please let me know. >> >> If you have Unicode experience and expertise, and would like to be, or >> would be willing to be, in the 'council of experts' for this project, >> please let me know. >> >> If you have comments or ideas on anything mentioned in this email >> >> In the first instance, the initiative's website will be: >> http://smalltalk.uk.to/unicode.html >> >> I have created a SqueakSource.com project called UnicodeSupport >> >> I want to avoid re-inventing any facilities which already exist. >> Except where they prevent us reaching the goals of: >> - sortable UTF8 strings >> - sortable UTF16 strings >> - equivalence testing of 2 UTF8 strings >> - equivalence testing of 2 UTF16 strings >> - round-tripping UTF8 strings through Smalltalk >> - roundtripping UTF16 strings through Smalltalk. >> As I understand it, we have limited Unicode support atm. >> >> Current state of play >> =============== >> ByteString gets converted to WideString when need is automagically >> detected. >> >> Is there anything else that currently exists? >> >> Definition of Terms >> ============== >> A quick definition of terms before I go any further: >> >> Standard terms from the Unicode standard >> =============================== >> a compatibility character : an additional encoding of a *normal* >> character, for compatibility and round-trip conversion purposes. For >> instance, a 1-byte encoding of a Latin character with a diacritic. >> >> Made-up terms >> ============ >> a convenience codepoint : a single codepoint which represents an item >> that is also encoded as a string of codepoints. >> >> (I tend to use the terms compatibility character and compatibility >> codepoint interchangably. The standard only refers to them as >> compatibility characters. However, the standard is determined to >> emphasise that characters are abstract and that codepoints are >> concrete. So I think it is often more useful and productive to think >> of compatibility or convenience codepoints). >> >> a composed character : a character made up of several codepoints >> >> Unicode encoding explained >> ===================== >> A convenience codepoint can therefore be thought of as a code point >> used for a character which also has a composed form. >> >> The way Unicode works is that sometimes you can encode a character in >> one byte, sometimes not. Sometimes you can encode it in two bytes, >> sometimes not. >> >> You can therefore have a long stream of ASCII which is single-byte >> Unicode. If there is an occasional Cyrillic or Greek character in the >> stream, it would be represented either by a compatibility character or >> by a multi-byte combination. >> >> Using compatibility characters can prevent proper sorting and >> equivalence testing. >> >> Using "pure" Unicode, ie. "normal encodings", can cause compatibility >> and round-tripping probelms. Although avoiding them can *also* cause >> compatibility issues and round-tripping problems. >> >> Currently my thinking is: >> >> a Utf8String class >> an Ordered collection, with 1 byte characters as the modal element, >> but short arrays of wider strings where necessary >> a Utf16String class >> an Ordered collection, with 2 byte characters as the modal element, >> but short arrays of wider strings >> beginning with a 2-byte endianness indicator. >> >> Utf8Strings sometimes need to be sortable, and sometimes need to be >> compatible. >> >> So my thinking is that Utf8String will contain convenience codepoints, >> for round-tripping. And where there are multiple convenience >> codepoints for a character, that it standardises on one. >> >> And that there is a Utf8SortableString which uses *only* normal >> characters. >> >> We then need methods to convert between the two. >> >> aUtf8String asUtf8SortableString >> >> and >> >> aUtf8SortableString asUtf8String >> >> >> Sort orders are culture and context dependent - Sweden and Germany >> have different sort orders for the same diacritic-ed characters. Some >> countries have one order in general usage, and another for specific >> usages, such as phone directories (e.g. UK and France) >> >> Similarly for Utf16 : Utf16String and Utf16SortableString and >> conversion methods >> >> A list of sorted words would be a SortedCollection, and there could be >> pre-prepared sortBlocks for them, e.g. frPhoneBookOrder, deOrder, >> seOrder, ukOrder, etc >> >> along the lines of >> aListOfWords := SortedCollection sortBlock: deOrder >> >> If a word is either a Utf8SortableString, or a well-formed Utf8String, >> then we can perform equivalence testing on them trivially. >> >> To make sure a Utf8String is well formed, we would need to have a way >> of cleaning up any convenience codepoints which were valid, but which >> were for a character which has multiple equally-valid alternative >> convenience codepoints, and for which the string currently had the >> "wrong" convenience codepoint. (i.e for any character with valid >> alternative convenience codepoints, we would choose one to be in the >> well-formed Utf8String, and we would need a method for cleaning the >> alternative convenience codepoints out of the string, and replacing >> them with the chosen approved convenience codepoint. >> >> aUtf8String cleanUtf8String >> >> With WideString, a lot of the issues disappear - except >> round-tripping(although I'm sure I have seen something recently about >> 4-byte strings that also have an additional bit. Which would make >> some Unicode characters 5-bytes long.) >> >> >> (I'm starting to zone out now - if I've overlooked anything - obvious, >> subtle, or somewhere in between, please let me know) >> >> Cheers, >> Euan >> >> > >

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Re: [Unicode] Update of page 'Multilingual Squeak'
by EuanM 07 Dec '15

07 Dec '15

Hi Hannes, It's looking like we should be able to conflate a bunch of existing facilities and code. The various Smalltalks seem to have approached Unicode like the old story of the blind men describing an elephant. There are lots of components when are usefully described and dealt with, and if we can just put them all together it'll will be less new work, and we should get a more portable outcome, and a more robust solution. On 7 December 2015 at 08:21, H. Hirzel <hannes.hirzel(a)gmail.com> wrote: > I updated the page > > 'Multilingual Squeak' > http://wiki.squeak.org/squeak/919 > > and some related pages. > > > Many pages have not been touched for 10 years. > I realized that a lot of infrastructure exists but seemingly people > are not aware of it or do not know how to use it. > > > In particular collation sequences are missing though there are > LanguageEnvironments. Pharo being a fork has most of it. It would be > an issue to check how much it differs and fold back or forth necessary > changes. The infrastructure as such seems to be capable. > > --Hannes

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Re: [Pharo-dev] Unicode Support
by EuanM 07 Dec '15

07 Dec '15

Hi Sven, okay I'm plodding my through https://tools.ietf.org/html/rfc3629 and https://en.wikipedia.org/wiki/UTF-8#Examples to see what's what. On 7 December 2015 at 11:01, Sven Van Caekenberghe <sven(a)stfx.eu> wrote: > >> On 07 Dec 2015, at 11:51, EuanM <euanmee(a)gmail.com> wrote: >> >> Verifying assumptions is the key reason why you should documents like >> this out for review. > > Fair enough, discussion can only help. > >> Sven - >> >> Cuis is encoded with ISO 8859-15 (aka ISO Latin 9) >> >> Sven, this is *NOT* as you state, ISO 99591, (and not as I stated, 8859-1). > > Ah, that was a typo, I meant, of course (and sorry for the confusion): > > 'Les élèves Français' encodeWith: #iso88591. > > "#[76 101 115 32 233 108 232 118 101 115 32 70 114 97 110 231 97 105 115]" > > 'Les élèves Français' utf8Encoded > > "#[76 101 115 32 195 169 108 195 168 118 101 115 32 70 114 97 110 195 167 97 105 115]" > > Or shorter, $é is encoded in ISO-88591-1 as #[233], but as #[195 169] in UTF-8. > > That Cuis chose ISO-8859-15 makes no real difference. > > The thing is: you started talking about UTF-8 encoded strings in the image, and then the difference between code point and encoding is really important. > > Only in ASCII is the encoding identical, not for anything else. > >> We caught the right specification bug for the wrong reason. >> >> Juan: "Cuis: Chose not to use Squeak approach. Chose to make the base >> image include and use only 1-byte strings. Chose to use ISO-8859-15" >> >> I have double-checked - each character encoded in ISO Latin 15 (ISO >> 8859-15) is exactly the character represented by the corresponding >> 1-byte codepoint in Unicode 0000 to 00FF, >> >> with the following exceptions: >> >> codepoint 20ac - Euro symbol >> character code a4 (replaces codepoint 00a4 generic currency symbol) >> >> codepoint 0160 Latin Upper Case S with Caron >> character code a6 (replaces codepoint 00A6 was | Unix pipe character) >> >> codepoint 0161 Latin Lower Case s with Caron >> character code a8 (replaces codepoint 00A8 was dierisis) >> >> codepoint 017d Latin Upper Case Z with Caron >> character code b4 (replaces codepoint 00b4 was Acute accent) >> >> codepoint 017e Latin Lower Case Z with Caron >> character code b8 (replaces codepoint 00b8 was cedilla) >> >> codepoint 0152 Upper Case OE ligature = Ethel >> character code bc (replaces codepoint 00bc was 1/4 symbol) >> >> codepoint 0153 Lower Case oe ligature = ethel >> character code bd (replaces codepoint 00bd was 1/2 symbol) >> >> codepoint 0178 Upper Case Y diaeresis >> character code be (replaces codepoint 00be was 3/4 symbol) >> >> Juan - I don't suppose we could persuade you to change to ISO Latin-1 >> from ISO Latin-9 ? >> >> It means we could run the same 1 byte string encoding across Cuis, >> Squeak, Pharo, and, as far as I can make out so far, Dolphin Smalltalk >> and Gnu Smalltalk. >> >> The downside would be that French Y diaeresis would lose the ability >> to use that character, along with users of oe, OE, and s, S, z, Z with >> caron. Along with the Euro. >> >> https://en.wikipedia.org/wiki/ISO/IEC_8859-15. >> >> I'm confident I understand the use of UTF-8 in principal. >> >> >> On 7 December 2015 at 08:27, Sven Van Caekenberghe <sven(a)stfx.eu> wrote: >>> I am sorry but one of your basic assumptions is completely wrong: >>> >>> 'Les élèves Français' encodeWith: #iso99591. >>> >>> => #[76 101 115 32 233 108 232 118 101 115 32 70 114 97 110 231 97 105 115] >>> >>> 'Les élèves Français' utf8Encoded. >>> >>> => #[76 101 115 32 195 169 108 195 168 118 101 115 32 70 114 97 110 195 167 97 105 115] >>> >>> ISO-9959-1 (~Latin1) is NOT AT ALL identical to UTF-8 in its upper, non-ACII part !! >>> >>> Or shorter, $é is encoded in ISO-9959-1 as #[233], but as #[195 169] in UTF-8. >>> >>> So more than half the points you make, or the facts that you state, are thus plain wrong. >>> >>> The only thing that is correct is that the code points are equal, but that is not the same as the encoding ! >>> >>> From this I am inclined to conclude that you do not fundamentally understand how UTF-8 works, which does not strike me as good basis to design something called a UTF8String. >>> >>> Sorry. >>> >>> PS: Note also that Cuis' choice to use ISO-9959-1 only is pretty limiting in a Unicode world. >>> >>>> On 07 Dec 2015, at 04:21, EuanM <euanmee(a)gmail.com> wrote: >>>> >>>> This a long email. A *lot* of it is encapsulated in the Venn diagram both: >>>> http://smalltalk.uk.to/unicode-utf8.html >>>> and my Smalltalk in Small Steps blog at: >>>> http://smalltalkinsmallsteps.blogspot.co.uk/2015/12/utf-8-for-cuis-pharo-an… >>>> >>>> My current thinking, and understanding. >>>> ============================== >>>> >>>> 0) a) ASCII and ISO-8859-1 consist of characters encoded in 1 byte. >>>> b) UTF-8 can encode all of those characters in 1 byte, but can >>>> prefer some of them to be encoded as sequences of multiple bytes. And >>>> can encode additional characters as sequences of multiple bytes. >>>> >>>> 1) Smalltalk has long had multiple String classes. >>>> >>>> 2) Any UTF16 Unicode codepoint which has a codepoint of 00nn hex >>>> is encoded as a UTF-8 codepoint of nn hex. >>>> >>>> 3) All valid ISO-8859-1 characters have a character code between 20 >>>> hex and 7E hex, or between A0 hex and FF hex. >>>> https://en.wikipedia.org/wiki/ISO/IEC_8859-1 >>>> >>>> 4) All valid ASCII characters have a character code between 00 hex and 7E hex. >>>> https://en.wikipedia.org/wiki/ASCII >>>> >>>> >>>> 5) a) All character codes which are defined within ISO-8859-1 and also >>>> defined within ASCII. (i.e. character codes 20 hex to 7E hex) are >>>> defined identically in both. >>>> >>>> b) All printable ASCII characters are defined identically in both >>>> ASCII and ISO-8859-1 >>>> >>>> 6) All character codes defined in ASCII (00 hex to 7E hex) are >>>> defined identically in Unicode UTF-8. >>>> >>>> 7) All character codes defined in ISO-8859-1 (20 hex - 7E hex ; A0 hex >>>> - FF hex ) are defined identically in UTF-8. >>>> >>>> 8) => some Unicode codepoints map to both ASCII and ISO-8859-1. >>>> all ASCII maps 1:1 to Unicode UTF-8 >>>> all ISO-8859-1 maps 1:1 to Unicode UTF-8 >>>> >>>> 9) All ByteStrings elements which are either a valid ISO-8859-1 >>>> character or a valid ASCII character are *also* a valid UTF-8 >>>> character. >>>> >>>> 10) ISO-8859-1 characters representing a character with a diacritic, >>>> or a two-character ligature, have no ASCII equivalent. In Unicode >>>> UTF-8, those character codes which are representing compound glyphs, >>>> are called "compatibility codepoints". >>>> >>>> 11) The preferred Unicode representation of the characters which have >>>> compatibility codepoints is as a a short set of codepoints >>>> representing the characters which are combined together to form the >>>> glyph of the convenience codepoint, as a sequence of bytes >>>> representing the component characters. >>>> >>>> >>>> 12) Some concrete examples: >>>> >>>> A - aka Upper Case A >>>> In ASCII, in ISO 8859-1 >>>> ASCII A - 41 hex >>>> ISO-8859-1 A - 41 hex >>>> UTF-8 A - 41 hex >>>> >>>> BEL (a bell sound, often invoked by a Ctrl-g keyboard chord) >>>> In ASCII, not in ISO 8859-1 >>>> ASCII : BEL - 07 hex >>>> ISO-8859-1 : 07 hex is not a valid character code >>>> UTF-8 : BEL - 07 hex >>>> >>>> £ (GBP currency symbol) >>>> In ISO-8859-1, not in ASCII >>>> ASCII : A3 hex is not a valid ASCII code >>>> UTF-8: £ - A3 hex >>>> ISO-8859-1: £ - A3 hex >>>> >>>> Upper Case C cedilla >>>> In ISO-8859-1, not in ASCII, in UTF-8 as a compatibility codepoint >>>> *and* a composed set of codepoints >>>> ASCII : C7 hex is not a valid ASCII character code >>>> ISO-8859-1 : Upper Case C cedilla - C7 hex >>>> UTF-8 : Upper Case C cedilla (compatibility codepoint) - C7 hex >>>> Unicode preferred Upper Case C cedilla (composed set of codepoints) >>>> Upper case C 0043 hex (Upper case C) >>>> followed by >>>> cedilla 00B8 hex (cedilla) >>>> >>>> 13) For any valid ASCII string *and* for any valid ISO-8859-1 string, >>>> aByteString is completely adequate for editing and display. >>>> >>>> 14) When sorting any valid ASCII string *or* any valid ISO-8859-1 >>>> string, upper and lower case versions of the same character will be >>>> treated differently. >>>> >>>> 15) When sorting any valid ISO-8859-1 string containing >>>> letter+diacritic combination glyphs or ligature combination glyphs, >>>> the glyphs in combination will treated differently to a "plain" glyph >>>> of the character >>>> i.e. "C" and "C cedilla" will be treated very differently. "ß" and >>>> "fs" will be treated very differently. >>>> >>>> 16) Different nations have different rules about where diacritic-ed >>>> characted and ligature pairs should be placed when in alphabetical >>>> order. >>>> >>>> 17) Some nations even have multiple standards - e.g. surnames >>>> beginning either "M superscript-c" or "M superscript-a superscript-c" >>>> are treated as beginning equivalently in UK phone directories, but not >>>> in other situations. >>>> >>>> >>>> Some practical upshots >>>> ================== >>>> >>>> 1) Cuis and its ISO-8859-1 encoding is *exactly* the same as UTF-8, >>>> for any single character it considers valid, or any ByteString it has >>>> made up of characters it considers valid. >>>> >>>> 2) Any ByteString is valid UTF-8 in any of Squeak, Pharo, Cuis or any >>>> other Smalltalk with a single byte ByteString following ASCII or >>>> ISO-8859-1. >>>> >>>> 3) Any Smalltalk (or derivative language) using ByteString can >>>> immediately consider it's ByteString as valid UTF-8, as long as it >>>> also considers the ByteSring as valid ASCII and/or ISO-8859-1. >>>> >>>> 4) All of those can be successfully exported to any system using UTF-8 >>>> (e.g. HTML). >>>> >>>> 5) To successfully *accept* all UTF-8 we much be able to do either: >>>> a) accept UTF-8 strings with composed characters >>>> b) convert UTF-8 strings with composed characters into UTF-8 strings >>>> that use *only* compatibility codepoints. >>>> >>>> >>>> Class + protocol proposals >>>> >>>> >>>> >>>> a Utf8CompatibilityString class. >>>> >>>> asByteString - ensure only compatibility codepoints are used. >>>> Ensure it doews not encode characters above 00FF hex. >>>> >>>> asIso8859String - ensures only compatibility codepoints are used, >>>> and that the characters are each valid ISO 8859-1 >>>> >>>> asAsciiString - ensures only characters 00hex - 7F hex are used. >>>> >>>> asUtf8ComposedIso8859String - ensures all compatibility codepoints >>>> are expanded into small OrderedCollections of codepoints >>>> >>>> a Utf8ComposedIso8859String class - will provide sortable and >>>> comparable UTF8 strings of all ASCII and ISO 8859-1 strings. >>>> >>>> Then a Utf8SortableCollection class - a collection of >>>> Utf8ComposedIso8859Strings words and phrases. >>>> >>>> Custom sortBlocks will define the applicable sort order. >>>> >>>> We can create a collection... a Dictionary, thinking about it, of >>>> named, prefabricated sortBlocks. >>>> >>>> This will work for all UTF8 strings of ISO-8859-1 and ASCII strings. >>>> >>>> If anyone has better names for the classes, please let me know. >>>> >>>> If anyone else wants to help >>>> - build these, >>>> - create SUnit tests for these >>>> - write documentation for these >>>> Please let me know. >>>> >>>> n.b. I have had absolutely no experience of Ropes. >>>> >>>> My own background with this stuff: In the early 90's as a Project >>>> Manager implementing office automation systems across a global >>>> company, with offices in the Americas, Western, Eastern and Central >>>> Europe, (including Slavic and Cyrillic users) nations, Japan and >>>> China. The mission-critical application was word-processing. >>>> >>>> Our offices were spread around the globe, and we needed those offices >>>> to successfully exchange documents with their sister offices, and with >>>> the customers in each region the offices were in. >>>> >>>> Unicode was then new, and our platform supplier was the NeXT >>>> Corporation, who had been founder members in of the Unicode Consortium >>>> in 1990. >>>> >>>> So far: I've read the latest version of the Unicode Standard (v8.0). >>>> This is freely downloadable. >>>> I've purchased a paper copy of an earlier release. New releases >>>> typically consist additional codespaces (i.e. alphabets). So old >>>> copies are useful, as well as cheap. (Paper copies of version 4.0 >>>> are available second-hand for < $10 / €10). >>>> >>>> The typical change with each release is the addition of further >>>> codespaces (i.e alphabets (more or less) ), so you don't lose a lot. >>>> (I'll be going through my V4.0 just to make sure) >>>> >>>> Cheers, >>>> Euan >>>> >>>> >>>> >>>> >>>> On 5 December 2015 at 13:08, stepharo <stepharo(a)free.fr> wrote: >>>>> Hi EuanM >>>>> >>>>> Le 4/12/15 12:42, EuanM a écrit : >>>>>> >>>>>> I'm currently groping my way to seeing how feature-complete our >>>>>> Unicode support is. I am doing this to establish what still needs to >>>>>> be done to provide full Unicode support. >>>>> >>>>> >>>>> this is great. Thanks for pushing this. I wrote and collected some roadmap >>>>> (analyses on different topics) >>>>> on the pharo github project feel free to add this one there. >>>>>> >>>>>> >>>>>> This seems to me to be an area where it would be best to write it >>>>>> once, and then have the same codebase incorporated into the Smalltalks >>>>>> that most share a common ancestry. >>>>>> >>>>>> I am keen to get: equality-testing for strings; sortability for >>>>>> strings which have ligatures and diacritic characters; and correct >>>>>> round-tripping of data. >>>>> >>>>> Go! >>>>> My suggestion is >>>>> start small >>>>> make steady progress >>>>> write tests >>>>> commit often :) >>>>> >>>>> Stef >>>>> >>>>> What is the french phoneBook ordering because this is the first time I hear >>>>> about it. >>>>> >>>>>> >>>>>> Call to action: >>>>>> ========== >>>>>> >>>>>> If you have comments on these proposals - such as "but we already have >>>>>> that facility" or "the reason we do not have these facilities is >>>>>> because they are dog-slow" - please let me know them. >>>>>> >>>>>> If you would like to help out, please let me know. >>>>>> >>>>>> If you have Unicode experience and expertise, and would like to be, or >>>>>> would be willing to be, in the 'council of experts' for this project, >>>>>> please let me know. >>>>>> >>>>>> If you have comments or ideas on anything mentioned in this email >>>>>> >>>>>> In the first instance, the initiative's website will be: >>>>>> http://smalltalk.uk.to/unicode.html >>>>>> >>>>>> I have created a SqueakSource.com project called UnicodeSupport >>>>>> >>>>>> I want to avoid re-inventing any facilities which already exist. >>>>>> Except where they prevent us reaching the goals of: >>>>>> - sortable UTF8 strings >>>>>> - sortable UTF16 strings >>>>>> - equivalence testing of 2 UTF8 strings >>>>>> - equivalence testing of 2 UTF16 strings >>>>>> - round-tripping UTF8 strings through Smalltalk >>>>>> - roundtripping UTF16 strings through Smalltalk. >>>>>> As I understand it, we have limited Unicode support atm. >>>>>> >>>>>> Current state of play >>>>>> =============== >>>>>> ByteString gets converted to WideString when need is automagically >>>>>> detected. >>>>>> >>>>>> Is there anything else that currently exists? >>>>>> >>>>>> Definition of Terms >>>>>> ============== >>>>>> A quick definition of terms before I go any further: >>>>>> >>>>>> Standard terms from the Unicode standard >>>>>> =============================== >>>>>> a compatibility character : an additional encoding of a *normal* >>>>>> character, for compatibility and round-trip conversion purposes. For >>>>>> instance, a 1-byte encoding of a Latin character with a diacritic. >>>>>> >>>>>> Made-up terms >>>>>> ============ >>>>>> a convenience codepoint : a single codepoint which represents an item >>>>>> that is also encoded as a string of codepoints. >>>>>> >>>>>> (I tend to use the terms compatibility character and compatibility >>>>>> codepoint interchangably. The standard only refers to them as >>>>>> compatibility characters. However, the standard is determined to >>>>>> emphasise that characters are abstract and that codepoints are >>>>>> concrete. So I think it is often more useful and productive to think >>>>>> of compatibility or convenience codepoints). >>>>>> >>>>>> a composed character : a character made up of several codepoints >>>>>> >>>>>> Unicode encoding explained >>>>>> ===================== >>>>>> A convenience codepoint can therefore be thought of as a code point >>>>>> used for a character which also has a composed form. >>>>>> >>>>>> The way Unicode works is that sometimes you can encode a character in >>>>>> one byte, sometimes not. Sometimes you can encode it in two bytes, >>>>>> sometimes not. >>>>>> >>>>>> You can therefore have a long stream of ASCII which is single-byte >>>>>> Unicode. If there is an occasional Cyrillic or Greek character in the >>>>>> stream, it would be represented either by a compatibility character or >>>>>> by a multi-byte combination. >>>>>> >>>>>> Using compatibility characters can prevent proper sorting and >>>>>> equivalence testing. >>>>>> >>>>>> Using "pure" Unicode, ie. "normal encodings", can cause compatibility >>>>>> and round-tripping probelms. Although avoiding them can *also* cause >>>>>> compatibility issues and round-tripping problems. >>>>>> >>>>>> Currently my thinking is: >>>>>> >>>>>> a Utf8String class >>>>>> an Ordered collection, with 1 byte characters as the modal element, >>>>>> but short arrays of wider strings where necessary >>>>>> a Utf16String class >>>>>> an Ordered collection, with 2 byte characters as the modal element, >>>>>> but short arrays of wider strings >>>>>> beginning with a 2-byte endianness indicator. >>>>>> >>>>>> Utf8Strings sometimes need to be sortable, and sometimes need to be >>>>>> compatible. >>>>>> >>>>>> So my thinking is that Utf8String will contain convenience codepoints, >>>>>> for round-tripping. And where there are multiple convenience >>>>>> codepoints for a character, that it standardises on one. >>>>>> >>>>>> And that there is a Utf8SortableString which uses *only* normal >>>>>> characters. >>>>>> >>>>>> We then need methods to convert between the two. >>>>>> >>>>>> aUtf8String asUtf8SortableString >>>>>> >>>>>> and >>>>>> >>>>>> aUtf8SortableString asUtf8String >>>>>> >>>>>> >>>>>> Sort orders are culture and context dependent - Sweden and Germany >>>>>> have different sort orders for the same diacritic-ed characters. Some >>>>>> countries have one order in general usage, and another for specific >>>>>> usages, such as phone directories (e.g. UK and France) >>>>>> >>>>>> Similarly for Utf16 : Utf16String and Utf16SortableString and >>>>>> conversion methods >>>>>> >>>>>> A list of sorted words would be a SortedCollection, and there could be >>>>>> pre-prepared sortBlocks for them, e.g. frPhoneBookOrder, deOrder, >>>>>> seOrder, ukOrder, etc >>>>>> >>>>>> along the lines of >>>>>> aListOfWords := SortedCollection sortBlock: deOrder >>>>>> >>>>>> If a word is either a Utf8SortableString, or a well-formed Utf8String, >>>>>> then we can perform equivalence testing on them trivially. >>>>>> >>>>>> To make sure a Utf8String is well formed, we would need to have a way >>>>>> of cleaning up any convenience codepoints which were valid, but which >>>>>> were for a character which has multiple equally-valid alternative >>>>>> convenience codepoints, and for which the string currently had the >>>>>> "wrong" convenience codepoint. (i.e for any character with valid >>>>>> alternative convenience codepoints, we would choose one to be in the >>>>>> well-formed Utf8String, and we would need a method for cleaning the >>>>>> alternative convenience codepoints out of the string, and replacing >>>>>> them with the chosen approved convenience codepoint. >>>>>> >>>>>> aUtf8String cleanUtf8String >>>>>> >>>>>> With WideString, a lot of the issues disappear - except >>>>>> round-tripping(although I'm sure I have seen something recently about >>>>>> 4-byte strings that also have an additional bit. Which would make >>>>>> some Unicode characters 5-bytes long.) >>>>>> >>>>>> >>>>>> (I'm starting to zone out now - if I've overlooked anything - obvious, >>>>>> subtle, or somewhere in between, please let me know) >>>>>> >>>>>> Cheers, >>>>>> Euan >>>>>> >>>>>> >>>>> >>>>> >>> >>>> On 07 Dec 2015, at 04:21, EuanM <euanmee(a)gmail.com> wrote: >>>> >>>> This a long email. A *lot* of it is encapsulated in the Venn diagram both: >>>> http://smalltalk.uk.to/unicode-utf8.html >>>> and my Smalltalk in Small Steps blog at: >>>> http://smalltalkinsmallsteps.blogspot.co.uk/2015/12/utf-8-for-cuis-pharo-an… >>>> >>>> My current thinking, and understanding. >>>> ============================== >>>> >>>> 0) a) ASCII and ISO-8859-1 consist of characters encoded in 1 byte. >>>> b) UTF-8 can encode all of those characters in 1 byte, but can >>>> prefer some of them to be encoded as sequences of multiple bytes. And >>>> can encode additional characters as sequences of multiple bytes. >>>> >>>> 1) Smalltalk has long had multiple String classes. >>>> >>>> 2) Any UTF16 Unicode codepoint which has a codepoint of 00nn hex >>>> is encoded as a UTF-8 codepoint of nn hex. >>>> >>>> 3) All valid ISO-8859-1 characters have a character code between 20 >>>> hex and 7E hex, or between A0 hex and FF hex. >>>> https://en.wikipedia.org/wiki/ISO/IEC_8859-1 >>>> >>>> 4) All valid ASCII characters have a character code between 00 hex and 7E hex. >>>> https://en.wikipedia.org/wiki/ASCII >>>> >>>> >>>> 5) a) All character codes which are defined within ISO-8859-1 and also >>>> defined within ASCII. (i.e. character codes 20 hex to 7E hex) are >>>> defined identically in both. >>>> >>>> b) All printable ASCII characters are defined identically in both >>>> ASCII and ISO-8859-1 >>>> >>>> 6) All character codes defined in ASCII (00 hex to 7E hex) are >>>> defined identically in Unicode UTF-8. >>>> >>>> 7) All character codes defined in ISO-8859-1 (20 hex - 7E hex ; A0 hex >>>> - FF hex ) are defined identically in UTF-8. >>>> >>>> 8) => some Unicode codepoints map to both ASCII and ISO-8859-1. >>>> all ASCII maps 1:1 to Unicode UTF-8 >>>> all ISO-8859-1 maps 1:1 to Unicode UTF-8 >>>> >>>> 9) All ByteStrings elements which are either a valid ISO-8859-1 >>>> character or a valid ASCII character are *also* a valid UTF-8 >>>> character. >>>> >>>> 10) ISO-8859-1 characters representing a character with a diacritic, >>>> or a two-character ligature, have no ASCII equivalent. In Unicode >>>> UTF-8, those character codes which are representing compound glyphs, >>>> are called "compatibility codepoints". >>>> >>>> 11) The preferred Unicode representation of the characters which have >>>> compatibility codepoints is as a a short set of codepoints >>>> representing the characters which are combined together to form the >>>> glyph of the convenience codepoint, as a sequence of bytes >>>> representing the component characters. >>>> >>>> >>>> 12) Some concrete examples: >>>> >>>> A - aka Upper Case A >>>> In ASCII, in ISO 8859-1 >>>> ASCII A - 41 hex >>>> ISO-8859-1 A - 41 hex >>>> UTF-8 A - 41 hex >>>> >>>> BEL (a bell sound, often invoked by a Ctrl-g keyboard chord) >>>> In ASCII, not in ISO 8859-1 >>>> ASCII : BEL - 07 hex >>>> ISO-8859-1 : 07 hex is not a valid character code >>>> UTF-8 : BEL - 07 hex >>>> >>>> £ (GBP currency symbol) >>>> In ISO-8859-1, not in ASCII >>>> ASCII : A3 hex is not a valid ASCII code >>>> UTF-8: £ - A3 hex >>>> ISO-8859-1: £ - A3 hex >>>> >>>> Upper Case C cedilla >>>> In ISO-8859-1, not in ASCII, in UTF-8 as a compatibility codepoint >>>> *and* a composed set of codepoints >>>> ASCII : C7 hex is not a valid ASCII character code >>>> ISO-8859-1 : Upper Case C cedilla - C7 hex >>>> UTF-8 : Upper Case C cedilla (compatibility codepoint) - C7 hex >>>> Unicode preferred Upper Case C cedilla (composed set of codepoints) >>>> Upper case C 0043 hex (Upper case C) >>>> followed by >>>> cedilla 00B8 hex (cedilla) >>>> >>>> 13) For any valid ASCII string *and* for any valid ISO-8859-1 string, >>>> aByteString is completely adequate for editing and display. >>>> >>>> 14) When sorting any valid ASCII string *or* any valid ISO-8859-1 >>>> string, upper and lower case versions of the same character will be >>>> treated differently. >>>> >>>> 15) When sorting any valid ISO-8859-1 string containing >>>> letter+diacritic combination glyphs or ligature combination glyphs, >>>> the glyphs in combination will treated differently to a "plain" glyph >>>> of the character >>>> i.e. "C" and "C cedilla" will be treated very differently. "ß" and >>>> "fs" will be treated very differently. >>>> >>>> 16) Different nations have different rules about where diacritic-ed >>>> characted and ligature pairs should be placed when in alphabetical >>>> order. >>>> >>>> 17) Some nations even have multiple standards - e.g. surnames >>>> beginning either "M superscript-c" or "M superscript-a superscript-c" >>>> are treated as beginning equivalently in UK phone directories, but not >>>> in other situations. >>>> >>>> >>>> Some practical upshots >>>> ================== >>>> >>>> 1) Cuis and its ISO-8859-1 encoding is *exactly* the same as UTF-8, >>>> for any single character it considers valid, or any ByteString it has >>>> made up of characters it considers valid. >>>> >>>> 2) Any ByteString is valid UTF-8 in any of Squeak, Pharo, Cuis or any >>>> other Smalltalk with a single byte ByteString following ASCII or >>>> ISO-8859-1. >>>> >>>> 3) Any Smalltalk (or derivative language) using ByteString can >>>> immediately consider it's ByteString as valid UTF-8, as long as it >>>> also considers the ByteSring as valid ASCII and/or ISO-8859-1. >>>> >>>> 4) All of those can be successfully exported to any system using UTF-8 >>>> (e.g. HTML). >>>> >>>> 5) To successfully *accept* all UTF-8 we much be able to do either: >>>> a) accept UTF-8 strings with composed characters >>>> b) convert UTF-8 strings with composed characters into UTF-8 strings >>>> that use *only* compatibility codepoints. >>>> >>>> >>>> Class + protocol proposals >>>> >>>> >>>> >>>> a Utf8CompatibilityString class. >>>> >>>> asByteString - ensure only compatibility codepoints are used. >>>> Ensure it doews not encode characters above 00FF hex. >>>> >>>> asIso8859String - ensures only compatibility codepoints are used, >>>> and that the characters are each valid ISO 8859-1 >>>> >>>> asAsciiString - ensures only characters 00hex - 7F hex are used. >>>> >>>> asUtf8ComposedIso8859String - ensures all compatibility codepoints >>>> are expanded into small OrderedCollections of codepoints >>>> >>>> a Utf8ComposedIso8859String class - will provide sortable and >>>> comparable UTF8 strings of all ASCII and ISO 8859-1 strings. >>>> >>>> Then a Utf8SortableCollection class - a collection of >>>> Utf8ComposedIso8859Strings words and phrases. >>>> >>>> Custom sortBlocks will define the applicable sort order. >>>> >>>> We can create a collection... a Dictionary, thinking about it, of >>>> named, prefabricated sortBlocks. >>>> >>>> This will work for all UTF8 strings of ISO-8859-1 and ASCII strings. >>>> >>>> If anyone has better names for the classes, please let me know. >>>> >>>> If anyone else wants to help >>>> - build these, >>>> - create SUnit tests for these >>>> - write documentation for these >>>> Please let me know. >>>> >>>> n.b. I have had absolutely no experience of Ropes. >>>> >>>> My own background with this stuff: In the early 90's as a Project >>>> Manager implementing office automation systems across a global >>>> company, with offices in the Americas, Western, Eastern and Central >>>> Europe, (including Slavic and Cyrillic users) nations, Japan and >>>> China. The mission-critical application was word-processing. >>>> >>>> Our offices were spread around the globe, and we needed those offices >>>> to successfully exchange documents with their sister offices, and with >>>> the customers in each region the offices were in. >>>> >>>> Unicode was then new, and our platform supplier was the NeXT >>>> Corporation, who had been founder members in of the Unicode Consortium >>>> in 1990. >>>> >>>> So far: I've read the latest version of the Unicode Standard (v8.0). >>>> This is freely downloadable. >>>> I've purchased a paper copy of an earlier release. New releases >>>> typically consist additional codespaces (i.e. alphabets). So old >>>> copies are useful, as well as cheap. (Paper copies of version 4.0 >>>> are available second-hand for < $10 / €10). >>>> >>>> The typical change with each release is the addition of further >>>> codespaces (i.e alphabets (more or less) ), so you don't lose a lot. >>>> (I'll be going through my V4.0 just to make sure) >>>> >>>> Cheers, >>>> Euan >>>> >>>> >>>> >>>> >>>> On 5 December 2015 at 13:08, stepharo <stepharo(a)free.fr> wrote: >>>>> Hi EuanM >>>>> >>>>> Le 4/12/15 12:42, EuanM a écrit : >>>>>> >>>>>> I'm currently groping my way to seeing how feature-complete our >>>>>> Unicode support is. I am doing this to establish what still needs to >>>>>> be done to provide full Unicode support. >>>>> >>>>> >>>>> this is great. Thanks for pushing this. I wrote and collected some roadmap >>>>> (analyses on different topics) >>>>> on the pharo github project feel free to add this one there. >>>>>> >>>>>> >>>>>> This seems to me to be an area where it would be best to write it >>>>>> once, and then have the same codebase incorporated into the Smalltalks >>>>>> that most share a common ancestry. >>>>>> >>>>>> I am keen to get: equality-testing for strings; sortability for >>>>>> strings which have ligatures and diacritic characters; and correct >>>>>> round-tripping of data. >>>>> >>>>> Go! >>>>> My suggestion is >>>>> start small >>>>> make steady progress >>>>> write tests >>>>> commit often :) >>>>> >>>>> Stef >>>>> >>>>> What is the french phoneBook ordering because this is the first time I hear >>>>> about it. >>>>> >>>>>> >>>>>> Call to action: >>>>>> ========== >>>>>> >>>>>> If you have comments on these proposals - such as "but we already have >>>>>> that facility" or "the reason we do not have these facilities is >>>>>> because they are dog-slow" - please let me know them. >>>>>> >>>>>> If you would like to help out, please let me know. >>>>>> >>>>>> If you have Unicode experience and expertise, and would like to be, or >>>>>> would be willing to be, in the 'council of experts' for this project, >>>>>> please let me know. >>>>>> >>>>>> If you have comments or ideas on anything mentioned in this email >>>>>> >>>>>> In the first instance, the initiative's website will be: >>>>>> http://smalltalk.uk.to/unicode.html >>>>>> >>>>>> I have created a SqueakSource.com project called UnicodeSupport >>>>>> >>>>>> I want to avoid re-inventing any facilities which already exist. >>>>>> Except where they prevent us reaching the goals of: >>>>>> - sortable UTF8 strings >>>>>> - sortable UTF16 strings >>>>>> - equivalence testing of 2 UTF8 strings >>>>>> - equivalence testing of 2 UTF16 strings >>>>>> - round-tripping UTF8 strings through Smalltalk >>>>>> - roundtripping UTF16 strings through Smalltalk. >>>>>> As I understand it, we have limited Unicode support atm. >>>>>> >>>>>> Current state of play >>>>>> =============== >>>>>> ByteString gets converted to WideString when need is automagically >>>>>> detected. >>>>>> >>>>>> Is there anything else that currently exists? >>>>>> >>>>>> Definition of Terms >>>>>> ============== >>>>>> A quick definition of terms before I go any further: >>>>>> >>>>>> Standard terms from the Unicode standard >>>>>> =============================== >>>>>> a compatibility character : an additional encoding of a *normal* >>>>>> character, for compatibility and round-trip conversion purposes. For >>>>>> instance, a 1-byte encoding of a Latin character with a diacritic. >>>>>> >>>>>> Made-up terms >>>>>> ============ >>>>>> a convenience codepoint : a single codepoint which represents an item >>>>>> that is also encoded as a string of codepoints. >>>>>> >>>>>> (I tend to use the terms compatibility character and compatibility >>>>>> codepoint interchangably. The standard only refers to them as >>>>>> compatibility characters. However, the standard is determined to >>>>>> emphasise that characters are abstract and that codepoints are >>>>>> concrete. So I think it is often more useful and productive to think >>>>>> of compatibility or convenience codepoints). >>>>>> >>>>>> a composed character : a character made up of several codepoints >>>>>> >>>>>> Unicode encoding explained >>>>>> ===================== >>>>>> A convenience codepoint can therefore be thought of as a code point >>>>>> used for a character which also has a composed form. >>>>>> >>>>>> The way Unicode works is that sometimes you can encode a character in >>>>>> one byte, sometimes not. Sometimes you can encode it in two bytes, >>>>>> sometimes not. >>>>>> >>>>>> You can therefore have a long stream of ASCII which is single-byte >>>>>> Unicode. If there is an occasional Cyrillic or Greek character in the >>>>>> stream, it would be represented either by a compatibility character or >>>>>> by a multi-byte combination. >>>>>> >>>>>> Using compatibility characters can prevent proper sorting and >>>>>> equivalence testing. >>>>>> >>>>>> Using "pure" Unicode, ie. "normal encodings", can cause compatibility >>>>>> and round-tripping probelms. Although avoiding them can *also* cause >>>>>> compatibility issues and round-tripping problems. >>>>>> >>>>>> Currently my thinking is: >>>>>> >>>>>> a Utf8String class >>>>>> an Ordered collection, with 1 byte characters as the modal element, >>>>>> but short arrays of wider strings where necessary >>>>>> a Utf16String class >>>>>> an Ordered collection, with 2 byte characters as the modal element, >>>>>> but short arrays of wider strings >>>>>> beginning with a 2-byte endianness indicator. >>>>>> >>>>>> Utf8Strings sometimes need to be sortable, and sometimes need to be >>>>>> compatible. >>>>>> >>>>>> So my thinking is that Utf8String will contain convenience codepoints, >>>>>> for round-tripping. And where there are multiple convenience >>>>>> codepoints for a character, that it standardises on one. >>>>>> >>>>>> And that there is a Utf8SortableString which uses *only* normal >>>>>> characters. >>>>>> >>>>>> We then need methods to convert between the two. >>>>>> >>>>>> aUtf8String asUtf8SortableString >>>>>> >>>>>> and >>>>>> >>>>>> aUtf8SortableString asUtf8String >>>>>> >>>>>> >>>>>> Sort orders are culture and context dependent - Sweden and Germany >>>>>> have different sort orders for the same diacritic-ed characters. Some >>>>>> countries have one order in general usage, and another for specific >>>>>> usages, such as phone directories (e.g. UK and France) >>>>>> >>>>>> Similarly for Utf16 : Utf16String and Utf16SortableString and >>>>>> conversion methods >>>>>> >>>>>> A list of sorted words would be a SortedCollection, and there could be >>>>>> pre-prepared sortBlocks for them, e.g. frPhoneBookOrder, deOrder, >>>>>> seOrder, ukOrder, etc >>>>>> >>>>>> along the lines of >>>>>> aListOfWords := SortedCollection sortBlock: deOrder >>>>>> >>>>>> If a word is either a Utf8SortableString, or a well-formed Utf8String, >>>>>> then we can perform equivalence testing on them trivially. >>>>>> >>>>>> To make sure a Utf8String is well formed, we would need to have a way >>>>>> of cleaning up any convenience codepoints which were valid, but which >>>>>> were for a character which has multiple equally-valid alternative >>>>>> convenience codepoints, and for which the string currently had the >>>>>> "wrong" convenience codepoint. (i.e for any character with valid >>>>>> alternative convenience codepoints, we would choose one to be in the >>>>>> well-formed Utf8String, and we would need a method for cleaning the >>>>>> alternative convenience codepoints out of the string, and replacing >>>>>> them with the chosen approved convenience codepoint. >>>>>> >>>>>> aUtf8String cleanUtf8String >>>>>> >>>>>> With WideString, a lot of the issues disappear - except >>>>>> round-tripping(although I'm sure I have seen something recently about >>>>>> 4-byte strings that also have an additional bit. Which would make >>>>>> some Unicode characters 5-bytes long.) >>>>>> >>>>>> >>>>>> (I'm starting to zone out now - if I've overlooked anything - obvious, >>>>>> subtle, or somewhere in between, please let me know) >>>>>> >>>>>> Cheers, >>>>>> Euan >>>>>> >>>>>> >>>>> >>>>> >>>> >>> >>> >> > >

1 0

Re: [Pharo-dev] Unicode Support
by EuanM 07 Dec '15

07 Dec '15

As for the issue of lower case e acute, it is compatibility codepoint 00e9 hex and therefore encodable in UTF-8 as compatibility codepoint e9 hex and as the composed character #(0065 00b4) (all in hex) and as the same composed character as both #(feff 0065 00b4) and #(ffef 0065 00b4) when endianness markers are included and as I understand it, should also be legitimate to encode it in UTF8 as a composed character #(65 b4) (all hex) etc On 7 December 2015 at 08:27, Sven Van Caekenberghe <sven(a)stfx.eu> wrote: > I am sorry but one of your basic assumptions is completely wrong: > > 'Les élèves Français' encodeWith: #iso99591. > > => #[76 101 115 32 233 108 232 118 101 115 32 70 114 97 110 231 97 105 115] > > 'Les élèves Français' utf8Encoded. > > => #[76 101 115 32 195 169 108 195 168 118 101 115 32 70 114 97 110 195 167 97 105 115] > > ISO-9959-1 (~Latin1) is NOT AT ALL identical to UTF-8 in its upper, non-ACII part !! > > Or shorter, $é is encoded in ISO-9959-1 as #[233], but as #[195 169] in UTF-8. > > So more than half the points you make, or the facts that you state, are thus plain wrong. > > The only thing that is correct is that the code points are equal, but that is not the same as the encoding ! > > From this I am inclined to conclude that you do not fundamentally understand how UTF-8 works, which does not strike me as good basis to design something called a UTF8String. > > Sorry. > > PS: Note also that Cuis' choice to use ISO-9959-1 only is pretty limiting in a Unicode world. > >> On 07 Dec 2015, at 04:21, EuanM <euanmee(a)gmail.com> wrote: >> >> This a long email. A *lot* of it is encapsulated in the Venn diagram both: >> http://smalltalk.uk.to/unicode-utf8.html >> and my Smalltalk in Small Steps blog at: >> http://smalltalkinsmallsteps.blogspot.co.uk/2015/12/utf-8-for-cuis-pharo-an… >> >> My current thinking, and understanding. >> ============================== >> >> 0) a) ASCII and ISO-8859-1 consist of characters encoded in 1 byte. >> b) UTF-8 can encode all of those characters in 1 byte, but can >> prefer some of them to be encoded as sequences of multiple bytes. And >> can encode additional characters as sequences of multiple bytes. >> >> 1) Smalltalk has long had multiple String classes. >> >> 2) Any UTF16 Unicode codepoint which has a codepoint of 00nn hex >> is encoded as a UTF-8 codepoint of nn hex. >> >> 3) All valid ISO-8859-1 characters have a character code between 20 >> hex and 7E hex, or between A0 hex and FF hex. >> https://en.wikipedia.org/wiki/ISO/IEC_8859-1 >> >> 4) All valid ASCII characters have a character code between 00 hex and 7E hex. >> https://en.wikipedia.org/wiki/ASCII >> >> >> 5) a) All character codes which are defined within ISO-8859-1 and also >> defined within ASCII. (i.e. character codes 20 hex to 7E hex) are >> defined identically in both. >> >> b) All printable ASCII characters are defined identically in both >> ASCII and ISO-8859-1 >> >> 6) All character codes defined in ASCII (00 hex to 7E hex) are >> defined identically in Unicode UTF-8. >> >> 7) All character codes defined in ISO-8859-1 (20 hex - 7E hex ; A0 hex >> - FF hex ) are defined identically in UTF-8. >> >> 8) => some Unicode codepoints map to both ASCII and ISO-8859-1. >> all ASCII maps 1:1 to Unicode UTF-8 >> all ISO-8859-1 maps 1:1 to Unicode UTF-8 >> >> 9) All ByteStrings elements which are either a valid ISO-8859-1 >> character or a valid ASCII character are *also* a valid UTF-8 >> character. >> >> 10) ISO-8859-1 characters representing a character with a diacritic, >> or a two-character ligature, have no ASCII equivalent. In Unicode >> UTF-8, those character codes which are representing compound glyphs, >> are called "compatibility codepoints". >> >> 11) The preferred Unicode representation of the characters which have >> compatibility codepoints is as a a short set of codepoints >> representing the characters which are combined together to form the >> glyph of the convenience codepoint, as a sequence of bytes >> representing the component characters. >> >> >> 12) Some concrete examples: >> >> A - aka Upper Case A >> In ASCII, in ISO 8859-1 >> ASCII A - 41 hex >> ISO-8859-1 A - 41 hex >> UTF-8 A - 41 hex >> >> BEL (a bell sound, often invoked by a Ctrl-g keyboard chord) >> In ASCII, not in ISO 8859-1 >> ASCII : BEL - 07 hex >> ISO-8859-1 : 07 hex is not a valid character code >> UTF-8 : BEL - 07 hex >> >> £ (GBP currency symbol) >> In ISO-8859-1, not in ASCII >> ASCII : A3 hex is not a valid ASCII code >> UTF-8: £ - A3 hex >> ISO-8859-1: £ - A3 hex >> >> Upper Case C cedilla >> In ISO-8859-1, not in ASCII, in UTF-8 as a compatibility codepoint >> *and* a composed set of codepoints >> ASCII : C7 hex is not a valid ASCII character code >> ISO-8859-1 : Upper Case C cedilla - C7 hex >> UTF-8 : Upper Case C cedilla (compatibility codepoint) - C7 hex >> Unicode preferred Upper Case C cedilla (composed set of codepoints) >> Upper case C 0043 hex (Upper case C) >> followed by >> cedilla 00B8 hex (cedilla) >> >> 13) For any valid ASCII string *and* for any valid ISO-8859-1 string, >> aByteString is completely adequate for editing and display. >> >> 14) When sorting any valid ASCII string *or* any valid ISO-8859-1 >> string, upper and lower case versions of the same character will be >> treated differently. >> >> 15) When sorting any valid ISO-8859-1 string containing >> letter+diacritic combination glyphs or ligature combination glyphs, >> the glyphs in combination will treated differently to a "plain" glyph >> of the character >> i.e. "C" and "C cedilla" will be treated very differently. "ß" and >> "fs" will be treated very differently. >> >> 16) Different nations have different rules about where diacritic-ed >> characted and ligature pairs should be placed when in alphabetical >> order. >> >> 17) Some nations even have multiple standards - e.g. surnames >> beginning either "M superscript-c" or "M superscript-a superscript-c" >> are treated as beginning equivalently in UK phone directories, but not >> in other situations. >> >> >> Some practical upshots >> ================== >> >> 1) Cuis and its ISO-8859-1 encoding is *exactly* the same as UTF-8, >> for any single character it considers valid, or any ByteString it has >> made up of characters it considers valid. >> >> 2) Any ByteString is valid UTF-8 in any of Squeak, Pharo, Cuis or any >> other Smalltalk with a single byte ByteString following ASCII or >> ISO-8859-1. >> >> 3) Any Smalltalk (or derivative language) using ByteString can >> immediately consider it's ByteString as valid UTF-8, as long as it >> also considers the ByteSring as valid ASCII and/or ISO-8859-1. >> >> 4) All of those can be successfully exported to any system using UTF-8 >> (e.g. HTML). >> >> 5) To successfully *accept* all UTF-8 we much be able to do either: >> a) accept UTF-8 strings with composed characters >> b) convert UTF-8 strings with composed characters into UTF-8 strings >> that use *only* compatibility codepoints. >> >> >> Class + protocol proposals >> >> >> >> a Utf8CompatibilityString class. >> >> asByteString - ensure only compatibility codepoints are used. >> Ensure it doews not encode characters above 00FF hex. >> >> asIso8859String - ensures only compatibility codepoints are used, >> and that the characters are each valid ISO 8859-1 >> >> asAsciiString - ensures only characters 00hex - 7F hex are used. >> >> asUtf8ComposedIso8859String - ensures all compatibility codepoints >> are expanded into small OrderedCollections of codepoints >> >> a Utf8ComposedIso8859String class - will provide sortable and >> comparable UTF8 strings of all ASCII and ISO 8859-1 strings. >> >> Then a Utf8SortableCollection class - a collection of >> Utf8ComposedIso8859Strings words and phrases. >> >> Custom sortBlocks will define the applicable sort order. >> >> We can create a collection... a Dictionary, thinking about it, of >> named, prefabricated sortBlocks. >> >> This will work for all UTF8 strings of ISO-8859-1 and ASCII strings. >> >> If anyone has better names for the classes, please let me know. >> >> If anyone else wants to help >> - build these, >> - create SUnit tests for these >> - write documentation for these >> Please let me know. >> >> n.b. I have had absolutely no experience of Ropes. >> >> My own background with this stuff: In the early 90's as a Project >> Manager implementing office automation systems across a global >> company, with offices in the Americas, Western, Eastern and Central >> Europe, (including Slavic and Cyrillic users) nations, Japan and >> China. The mission-critical application was word-processing. >> >> Our offices were spread around the globe, and we needed those offices >> to successfully exchange documents with their sister offices, and with >> the customers in each region the offices were in. >> >> Unicode was then new, and our platform supplier was the NeXT >> Corporation, who had been founder members in of the Unicode Consortium >> in 1990. >> >> So far: I've read the latest version of the Unicode Standard (v8.0). >> This is freely downloadable. >> I've purchased a paper copy of an earlier release. New releases >> typically consist additional codespaces (i.e. alphabets). So old >> copies are useful, as well as cheap. (Paper copies of version 4.0 >> are available second-hand for < $10 / €10). >> >> The typical change with each release is the addition of further >> codespaces (i.e alphabets (more or less) ), so you don't lose a lot. >> (I'll be going through my V4.0 just to make sure) >> >> Cheers, >> Euan >> >> >> >> >> On 5 December 2015 at 13:08, stepharo <stepharo(a)free.fr> wrote: >>> Hi EuanM >>> >>> Le 4/12/15 12:42, EuanM a écrit : >>>> >>>> I'm currently groping my way to seeing how feature-complete our >>>> Unicode support is. I am doing this to establish what still needs to >>>> be done to provide full Unicode support. >>> >>> >>> this is great. Thanks for pushing this. I wrote and collected some roadmap >>> (analyses on different topics) >>> on the pharo github project feel free to add this one there. >>>> >>>> >>>> This seems to me to be an area where it would be best to write it >>>> once, and then have the same codebase incorporated into the Smalltalks >>>> that most share a common ancestry. >>>> >>>> I am keen to get: equality-testing for strings; sortability for >>>> strings which have ligatures and diacritic characters; and correct >>>> round-tripping of data. >>> >>> Go! >>> My suggestion is >>> start small >>> make steady progress >>> write tests >>> commit often :) >>> >>> Stef >>> >>> What is the french phoneBook ordering because this is the first time I hear >>> about it. >>> >>>> >>>> Call to action: >>>> ========== >>>> >>>> If you have comments on these proposals - such as "but we already have >>>> that facility" or "the reason we do not have these facilities is >>>> because they are dog-slow" - please let me know them. >>>> >>>> If you would like to help out, please let me know. >>>> >>>> If you have Unicode experience and expertise, and would like to be, or >>>> would be willing to be, in the 'council of experts' for this project, >>>> please let me know. >>>> >>>> If you have comments or ideas on anything mentioned in this email >>>> >>>> In the first instance, the initiative's website will be: >>>> http://smalltalk.uk.to/unicode.html >>>> >>>> I have created a SqueakSource.com project called UnicodeSupport >>>> >>>> I want to avoid re-inventing any facilities which already exist. >>>> Except where they prevent us reaching the goals of: >>>> - sortable UTF8 strings >>>> - sortable UTF16 strings >>>> - equivalence testing of 2 UTF8 strings >>>> - equivalence testing of 2 UTF16 strings >>>> - round-tripping UTF8 strings through Smalltalk >>>> - roundtripping UTF16 strings through Smalltalk. >>>> As I understand it, we have limited Unicode support atm. >>>> >>>> Current state of play >>>> =============== >>>> ByteString gets converted to WideString when need is automagically >>>> detected. >>>> >>>> Is there anything else that currently exists? >>>> >>>> Definition of Terms >>>> ============== >>>> A quick definition of terms before I go any further: >>>> >>>> Standard terms from the Unicode standard >>>> =============================== >>>> a compatibility character : an additional encoding of a *normal* >>>> character, for compatibility and round-trip conversion purposes. For >>>> instance, a 1-byte encoding of a Latin character with a diacritic. >>>> >>>> Made-up terms >>>> ============ >>>> a convenience codepoint : a single codepoint which represents an item >>>> that is also encoded as a string of codepoints. >>>> >>>> (I tend to use the terms compatibility character and compatibility >>>> codepoint interchangably. The standard only refers to them as >>>> compatibility characters. However, the standard is determined to >>>> emphasise that characters are abstract and that codepoints are >>>> concrete. So I think it is often more useful and productive to think >>>> of compatibility or convenience codepoints). >>>> >>>> a composed character : a character made up of several codepoints >>>> >>>> Unicode encoding explained >>>> ===================== >>>> A convenience codepoint can therefore be thought of as a code point >>>> used for a character which also has a composed form. >>>> >>>> The way Unicode works is that sometimes you can encode a character in >>>> one byte, sometimes not. Sometimes you can encode it in two bytes, >>>> sometimes not. >>>> >>>> You can therefore have a long stream of ASCII which is single-byte >>>> Unicode. If there is an occasional Cyrillic or Greek character in the >>>> stream, it would be represented either by a compatibility character or >>>> by a multi-byte combination. >>>> >>>> Using compatibility characters can prevent proper sorting and >>>> equivalence testing. >>>> >>>> Using "pure" Unicode, ie. "normal encodings", can cause compatibility >>>> and round-tripping probelms. Although avoiding them can *also* cause >>>> compatibility issues and round-tripping problems. >>>> >>>> Currently my thinking is: >>>> >>>> a Utf8String class >>>> an Ordered collection, with 1 byte characters as the modal element, >>>> but short arrays of wider strings where necessary >>>> a Utf16String class >>>> an Ordered collection, with 2 byte characters as the modal element, >>>> but short arrays of wider strings >>>> beginning with a 2-byte endianness indicator. >>>> >>>> Utf8Strings sometimes need to be sortable, and sometimes need to be >>>> compatible. >>>> >>>> So my thinking is that Utf8String will contain convenience codepoints, >>>> for round-tripping. And where there are multiple convenience >>>> codepoints for a character, that it standardises on one. >>>> >>>> And that there is a Utf8SortableString which uses *only* normal >>>> characters. >>>> >>>> We then need methods to convert between the two. >>>> >>>> aUtf8String asUtf8SortableString >>>> >>>> and >>>> >>>> aUtf8SortableString asUtf8String >>>> >>>> >>>> Sort orders are culture and context dependent - Sweden and Germany >>>> have different sort orders for the same diacritic-ed characters. Some >>>> countries have one order in general usage, and another for specific >>>> usages, such as phone directories (e.g. UK and France) >>>> >>>> Similarly for Utf16 : Utf16String and Utf16SortableString and >>>> conversion methods >>>> >>>> A list of sorted words would be a SortedCollection, and there could be >>>> pre-prepared sortBlocks for them, e.g. frPhoneBookOrder, deOrder, >>>> seOrder, ukOrder, etc >>>> >>>> along the lines of >>>> aListOfWords := SortedCollection sortBlock: deOrder >>>> >>>> If a word is either a Utf8SortableString, or a well-formed Utf8String, >>>> then we can perform equivalence testing on them trivially. >>>> >>>> To make sure a Utf8String is well formed, we would need to have a way >>>> of cleaning up any convenience codepoints which were valid, but which >>>> were for a character which has multiple equally-valid alternative >>>> convenience codepoints, and for which the string currently had the >>>> "wrong" convenience codepoint. (i.e for any character with valid >>>> alternative convenience codepoints, we would choose one to be in the >>>> well-formed Utf8String, and we would need a method for cleaning the >>>> alternative convenience codepoints out of the string, and replacing >>>> them with the chosen approved convenience codepoint. >>>> >>>> aUtf8String cleanUtf8String >>>> >>>> With WideString, a lot of the issues disappear - except >>>> round-tripping(although I'm sure I have seen something recently about >>>> 4-byte strings that also have an additional bit. Which would make >>>> some Unicode characters 5-bytes long.) >>>> >>>> >>>> (I'm starting to zone out now - if I've overlooked anything - obvious, >>>> subtle, or somewhere in between, please let me know) >>>> >>>> Cheers, >>>> Euan >>>> >>>> >>> >>> > >> On 07 Dec 2015, at 04:21, EuanM <euanmee(a)gmail.com> wrote: >> >> This a long email. A *lot* of it is encapsulated in the Venn diagram both: >> http://smalltalk.uk.to/unicode-utf8.html >> and my Smalltalk in Small Steps blog at: >> http://smalltalkinsmallsteps.blogspot.co.uk/2015/12/utf-8-for-cuis-pharo-an… >> >> My current thinking, and understanding. >> ============================== >> >> 0) a) ASCII and ISO-8859-1 consist of characters encoded in 1 byte. >> b) UTF-8 can encode all of those characters in 1 byte, but can >> prefer some of them to be encoded as sequences of multiple bytes. And >> can encode additional characters as sequences of multiple bytes. >> >> 1) Smalltalk has long had multiple String classes. >> >> 2) Any UTF16 Unicode codepoint which has a codepoint of 00nn hex >> is encoded as a UTF-8 codepoint of nn hex. >> >> 3) All valid ISO-8859-1 characters have a character code between 20 >> hex and 7E hex, or between A0 hex and FF hex. >> https://en.wikipedia.org/wiki/ISO/IEC_8859-1 >> >> 4) All valid ASCII characters have a character code between 00 hex and 7E hex. >> https://en.wikipedia.org/wiki/ASCII >> >> >> 5) a) All character codes which are defined within ISO-8859-1 and also >> defined within ASCII. (i.e. character codes 20 hex to 7E hex) are >> defined identically in both. >> >> b) All printable ASCII characters are defined identically in both >> ASCII and ISO-8859-1 >> >> 6) All character codes defined in ASCII (00 hex to 7E hex) are >> defined identically in Unicode UTF-8. >> >> 7) All character codes defined in ISO-8859-1 (20 hex - 7E hex ; A0 hex >> - FF hex ) are defined identically in UTF-8. >> >> 8) => some Unicode codepoints map to both ASCII and ISO-8859-1. >> all ASCII maps 1:1 to Unicode UTF-8 >> all ISO-8859-1 maps 1:1 to Unicode UTF-8 >> >> 9) All ByteStrings elements which are either a valid ISO-8859-1 >> character or a valid ASCII character are *also* a valid UTF-8 >> character. >> >> 10) ISO-8859-1 characters representing a character with a diacritic, >> or a two-character ligature, have no ASCII equivalent. In Unicode >> UTF-8, those character codes which are representing compound glyphs, >> are called "compatibility codepoints". >> >> 11) The preferred Unicode representation of the characters which have >> compatibility codepoints is as a a short set of codepoints >> representing the characters which are combined together to form the >> glyph of the convenience codepoint, as a sequence of bytes >> representing the component characters. >> >> >> 12) Some concrete examples: >> >> A - aka Upper Case A >> In ASCII, in ISO 8859-1 >> ASCII A - 41 hex >> ISO-8859-1 A - 41 hex >> UTF-8 A - 41 hex >> >> BEL (a bell sound, often invoked by a Ctrl-g keyboard chord) >> In ASCII, not in ISO 8859-1 >> ASCII : BEL - 07 hex >> ISO-8859-1 : 07 hex is not a valid character code >> UTF-8 : BEL - 07 hex >> >> £ (GBP currency symbol) >> In ISO-8859-1, not in ASCII >> ASCII : A3 hex is not a valid ASCII code >> UTF-8: £ - A3 hex >> ISO-8859-1: £ - A3 hex >> >> Upper Case C cedilla >> In ISO-8859-1, not in ASCII, in UTF-8 as a compatibility codepoint >> *and* a composed set of codepoints >> ASCII : C7 hex is not a valid ASCII character code >> ISO-8859-1 : Upper Case C cedilla - C7 hex >> UTF-8 : Upper Case C cedilla (compatibility codepoint) - C7 hex >> Unicode preferred Upper Case C cedilla (composed set of codepoints) >> Upper case C 0043 hex (Upper case C) >> followed by >> cedilla 00B8 hex (cedilla) >> >> 13) For any valid ASCII string *and* for any valid ISO-8859-1 string, >> aByteString is completely adequate for editing and display. >> >> 14) When sorting any valid ASCII string *or* any valid ISO-8859-1 >> string, upper and lower case versions of the same character will be >> treated differently. >> >> 15) When sorting any valid ISO-8859-1 string containing >> letter+diacritic combination glyphs or ligature combination glyphs, >> the glyphs in combination will treated differently to a "plain" glyph >> of the character >> i.e. "C" and "C cedilla" will be treated very differently. "ß" and >> "fs" will be treated very differently. >> >> 16) Different nations have different rules about where diacritic-ed >> characted and ligature pairs should be placed when in alphabetical >> order. >> >> 17) Some nations even have multiple standards - e.g. surnames >> beginning either "M superscript-c" or "M superscript-a superscript-c" >> are treated as beginning equivalently in UK phone directories, but not >> in other situations. >> >> >> Some practical upshots >> ================== >> >> 1) Cuis and its ISO-8859-1 encoding is *exactly* the same as UTF-8, >> for any single character it considers valid, or any ByteString it has >> made up of characters it considers valid. >> >> 2) Any ByteString is valid UTF-8 in any of Squeak, Pharo, Cuis or any >> other Smalltalk with a single byte ByteString following ASCII or >> ISO-8859-1. >> >> 3) Any Smalltalk (or derivative language) using ByteString can >> immediately consider it's ByteString as valid UTF-8, as long as it >> also considers the ByteSring as valid ASCII and/or ISO-8859-1. >> >> 4) All of those can be successfully exported to any system using UTF-8 >> (e.g. HTML). >> >> 5) To successfully *accept* all UTF-8 we much be able to do either: >> a) accept UTF-8 strings with composed characters >> b) convert UTF-8 strings with composed characters into UTF-8 strings >> that use *only* compatibility codepoints. >> >> >> Class + protocol proposals >> >> >> >> a Utf8CompatibilityString class. >> >> asByteString - ensure only compatibility codepoints are used. >> Ensure it doews not encode characters above 00FF hex. >> >> asIso8859String - ensures only compatibility codepoints are used, >> and that the characters are each valid ISO 8859-1 >> >> asAsciiString - ensures only characters 00hex - 7F hex are used. >> >> asUtf8ComposedIso8859String - ensures all compatibility codepoints >> are expanded into small OrderedCollections of codepoints >> >> a Utf8ComposedIso8859String class - will provide sortable and >> comparable UTF8 strings of all ASCII and ISO 8859-1 strings. >> >> Then a Utf8SortableCollection class - a collection of >> Utf8ComposedIso8859Strings words and phrases. >> >> Custom sortBlocks will define the applicable sort order. >> >> We can create a collection... a Dictionary, thinking about it, of >> named, prefabricated sortBlocks. >> >> This will work for all UTF8 strings of ISO-8859-1 and ASCII strings. >> >> If anyone has better names for the classes, please let me know. >> >> If anyone else wants to help >> - build these, >> - create SUnit tests for these >> - write documentation for these >> Please let me know. >> >> n.b. I have had absolutely no experience of Ropes. >> >> My own background with this stuff: In the early 90's as a Project >> Manager implementing office automation systems across a global >> company, with offices in the Americas, Western, Eastern and Central >> Europe, (including Slavic and Cyrillic users) nations, Japan and >> China. The mission-critical application was word-processing. >> >> Our offices were spread around the globe, and we needed those offices >> to successfully exchange documents with their sister offices, and with >> the customers in each region the offices were in. >> >> Unicode was then new, and our platform supplier was the NeXT >> Corporation, who had been founder members in of the Unicode Consortium >> in 1990. >> >> So far: I've read the latest version of the Unicode Standard (v8.0). >> This is freely downloadable. >> I've purchased a paper copy of an earlier release. New releases >> typically consist additional codespaces (i.e. alphabets). So old >> copies are useful, as well as cheap. (Paper copies of version 4.0 >> are available second-hand for < $10 / €10). >> >> The typical change with each release is the addition of further >> codespaces (i.e alphabets (more or less) ), so you don't lose a lot. >> (I'll be going through my V4.0 just to make sure) >> >> Cheers, >> Euan >> >> >> >> >> On 5 December 2015 at 13:08, stepharo <stepharo(a)free.fr> wrote: >>> Hi EuanM >>> >>> Le 4/12/15 12:42, EuanM a écrit : >>>> >>>> I'm currently groping my way to seeing how feature-complete our >>>> Unicode support is. I am doing this to establish what still needs to >>>> be done to provide full Unicode support. >>> >>> >>> this is great. Thanks for pushing this. I wrote and collected some roadmap >>> (analyses on different topics) >>> on the pharo github project feel free to add this one there. >>>> >>>> >>>> This seems to me to be an area where it would be best to write it >>>> once, and then have the same codebase incorporated into the Smalltalks >>>> that most share a common ancestry. >>>> >>>> I am keen to get: equality-testing for strings; sortability for >>>> strings which have ligatures and diacritic characters; and correct >>>> round-tripping of data. >>> >>> Go! >>> My suggestion is >>> start small >>> make steady progress >>> write tests >>> commit often :) >>> >>> Stef >>> >>> What is the french phoneBook ordering because this is the first time I hear >>> about it. >>> >>>> >>>> Call to action: >>>> ========== >>>> >>>> If you have comments on these proposals - such as "but we already have >>>> that facility" or "the reason we do not have these facilities is >>>> because they are dog-slow" - please let me know them. >>>> >>>> If you would like to help out, please let me know. >>>> >>>> If you have Unicode experience and expertise, and would like to be, or >>>> would be willing to be, in the 'council of experts' for this project, >>>> please let me know. >>>> >>>> If you have comments or ideas on anything mentioned in this email >>>> >>>> In the first instance, the initiative's website will be: >>>> http://smalltalk.uk.to/unicode.html >>>> >>>> I have created a SqueakSource.com project called UnicodeSupport >>>> >>>> I want to avoid re-inventing any facilities which already exist. >>>> Except where they prevent us reaching the goals of: >>>> - sortable UTF8 strings >>>> - sortable UTF16 strings >>>> - equivalence testing of 2 UTF8 strings >>>> - equivalence testing of 2 UTF16 strings >>>> - round-tripping UTF8 strings through Smalltalk >>>> - roundtripping UTF16 strings through Smalltalk. >>>> As I understand it, we have limited Unicode support atm. >>>> >>>> Current state of play >>>> =============== >>>> ByteString gets converted to WideString when need is automagically >>>> detected. >>>> >>>> Is there anything else that currently exists? >>>> >>>> Definition of Terms >>>> ============== >>>> A quick definition of terms before I go any further: >>>> >>>> Standard terms from the Unicode standard >>>> =============================== >>>> a compatibility character : an additional encoding of a *normal* >>>> character, for compatibility and round-trip conversion purposes. For >>>> instance, a 1-byte encoding of a Latin character with a diacritic. >>>> >>>> Made-up terms >>>> ============ >>>> a convenience codepoint : a single codepoint which represents an item >>>> that is also encoded as a string of codepoints. >>>> >>>> (I tend to use the terms compatibility character and compatibility >>>> codepoint interchangably. The standard only refers to them as >>>> compatibility characters. However, the standard is determined to >>>> emphasise that characters are abstract and that codepoints are >>>> concrete. So I think it is often more useful and productive to think >>>> of compatibility or convenience codepoints). >>>> >>>> a composed character : a character made up of several codepoints >>>> >>>> Unicode encoding explained >>>> ===================== >>>> A convenience codepoint can therefore be thought of as a code point >>>> used for a character which also has a composed form. >>>> >>>> The way Unicode works is that sometimes you can encode a character in >>>> one byte, sometimes not. Sometimes you can encode it in two bytes, >>>> sometimes not. >>>> >>>> You can therefore have a long stream of ASCII which is single-byte >>>> Unicode. If there is an occasional Cyrillic or Greek character in the >>>> stream, it would be represented either by a compatibility character or >>>> by a multi-byte combination. >>>> >>>> Using compatibility characters can prevent proper sorting and >>>> equivalence testing. >>>> >>>> Using "pure" Unicode, ie. "normal encodings", can cause compatibility >>>> and round-tripping probelms. Although avoiding them can *also* cause >>>> compatibility issues and round-tripping problems. >>>> >>>> Currently my thinking is: >>>> >>>> a Utf8String class >>>> an Ordered collection, with 1 byte characters as the modal element, >>>> but short arrays of wider strings where necessary >>>> a Utf16String class >>>> an Ordered collection, with 2 byte characters as the modal element, >>>> but short arrays of wider strings >>>> beginning with a 2-byte endianness indicator. >>>> >>>> Utf8Strings sometimes need to be sortable, and sometimes need to be >>>> compatible. >>>> >>>> So my thinking is that Utf8String will contain convenience codepoints, >>>> for round-tripping. And where there are multiple convenience >>>> codepoints for a character, that it standardises on one. >>>> >>>> And that there is a Utf8SortableString which uses *only* normal >>>> characters. >>>> >>>> We then need methods to convert between the two. >>>> >>>> aUtf8String asUtf8SortableString >>>> >>>> and >>>> >>>> aUtf8SortableString asUtf8String >>>> >>>> >>>> Sort orders are culture and context dependent - Sweden and Germany >>>> have different sort orders for the same diacritic-ed characters. Some >>>> countries have one order in general usage, and another for specific >>>> usages, such as phone directories (e.g. UK and France) >>>> >>>> Similarly for Utf16 : Utf16String and Utf16SortableString and >>>> conversion methods >>>> >>>> A list of sorted words would be a SortedCollection, and there could be >>>> pre-prepared sortBlocks for them, e.g. frPhoneBookOrder, deOrder, >>>> seOrder, ukOrder, etc >>>> >>>> along the lines of >>>> aListOfWords := SortedCollection sortBlock: deOrder >>>> >>>> If a word is either a Utf8SortableString, or a well-formed Utf8String, >>>> then we can perform equivalence testing on them trivially. >>>> >>>> To make sure a Utf8String is well formed, we would need to have a way >>>> of cleaning up any convenience codepoints which were valid, but which >>>> were for a character which has multiple equally-valid alternative >>>> convenience codepoints, and for which the string currently had the >>>> "wrong" convenience codepoint. (i.e for any character with valid >>>> alternative convenience codepoints, we would choose one to be in the >>>> well-formed Utf8String, and we would need a method for cleaning the >>>> alternative convenience codepoints out of the string, and replacing >>>> them with the chosen approved convenience codepoint. >>>> >>>> aUtf8String cleanUtf8String >>>> >>>> With WideString, a lot of the issues disappear - except >>>> round-tripping(although I'm sure I have seen something recently about >>>> 4-byte strings that also have an additional bit. Which would make >>>> some Unicode characters 5-bytes long.) >>>> >>>> >>>> (I'm starting to zone out now - if I've overlooked anything - obvious, >>>> subtle, or somewhere in between, please let me know) >>>> >>>> Cheers, >>>> Euan >>>> >>>> >>> >>> >> > >

1 0

Re: [Pharo-dev] Unicode Support
by EuanM 07 Dec '15

07 Dec '15

Verifying assumptions is the key reason why you should documents like this out for review. Sven - Cuis is encoded with ISO 8859-15 (aka ISO Latin 9) Sven, this is *NOT* as you state, ISO 99591, (and not as I stated, 8859-1). We caught the right specification bug for the wrong reason. Juan: "Cuis: Chose not to use Squeak approach. Chose to make the base image include and use only 1-byte strings. Chose to use ISO-8859-15" I have double-checked - each character encoded in ISO Latin 15 (ISO 8859-15) is exactly the character represented by the corresponding 1-byte codepoint in Unicode 0000 to 00FF, with the following exceptions: codepoint 20ac - Euro symbol character code a4 (replaces codepoint 00a4 generic currency symbol) codepoint 0160 Latin Upper Case S with Caron character code a6 (replaces codepoint 00A6 was | Unix pipe character) codepoint 0161 Latin Lower Case s with Caron character code a8 (replaces codepoint 00A8 was dierisis) codepoint 017d Latin Upper Case Z with Caron character code b4 (replaces codepoint 00b4 was Acute accent) codepoint 017e Latin Lower Case Z with Caron character code b8 (replaces codepoint 00b8 was cedilla) codepoint 0152 Upper Case OE ligature = Ethel character code bc (replaces codepoint 00bc was 1/4 symbol) codepoint 0153 Lower Case oe ligature = ethel character code bd (replaces codepoint 00bd was 1/2 symbol) codepoint 0178 Upper Case Y diaeresis character code be (replaces codepoint 00be was 3/4 symbol) Juan - I don't suppose we could persuade you to change to ISO Latin-1 from ISO Latin-9 ? It means we could run the same 1 byte string encoding across Cuis, Squeak, Pharo, and, as far as I can make out so far, Dolphin Smalltalk and Gnu Smalltalk. The downside would be that French Y diaeresis would lose the ability to use that character, along with users of oe, OE, and s, S, z, Z with caron. Along with the Euro. https://en.wikipedia.org/wiki/ISO/IEC_8859-15. I'm confident I understand the use of UTF-8 in principle. On 7 December 2015 at 08:27, Sven Van Caekenberghe <sven(a)stfx.eu> wrote: > I am sorry but one of your basic assumptions is completely wrong: > > 'Les élèves Français' encodeWith: #iso99591. > > => #[76 101 115 32 233 108 232 118 101 115 32 70 114 97 110 231 97 105 115] > > 'Les élèves Français' utf8Encoded. > > => #[76 101 115 32 195 169 108 195 168 118 101 115 32 70 114 97 110 195 167 97 105 115] > > ISO-9959-1 (~Latin1) is NOT AT ALL identical to UTF-8 in its upper, non-ACII part !! > > Or shorter, $é is encoded in ISO-9959-1 as #[233], but as #[195 169] in UTF-8. > > So more than half the points you make, or the facts that you state, are thus plain wrong. > > The only thing that is correct is that the code points are equal, but that is not the same as the encoding ! > > From this I am inclined to conclude that you do not fundamentally understand how UTF-8 works, which does not strike me as good basis to design something called a UTF8String. > > Sorry. > > PS: Note also that Cuis' choice to use ISO-9959-1 only is pretty limiting in a Unicode world. > >> On 07 Dec 2015, at 04:21, EuanM <euanmee(a)gmail.com> wrote: >> >> This a long email. A *lot* of it is encapsulated in the Venn diagram both: >> http://smalltalk.uk.to/unicode-utf8.html >> and my Smalltalk in Small Steps blog at: >> http://smalltalkinsmallsteps.blogspot.co.uk/2015/12/utf-8-for-cuis-pharo-an… >> >> My current thinking, and understanding. >> ============================== >> >> 0) a) ASCII and ISO-8859-1 consist of characters encoded in 1 byte. >> b) UTF-8 can encode all of those characters in 1 byte, but can >> prefer some of them to be encoded as sequences of multiple bytes. And >> can encode additional characters as sequences of multiple bytes. >> >> 1) Smalltalk has long had multiple String classes. >> >> 2) Any UTF16 Unicode codepoint which has a codepoint of 00nn hex >> is encoded as a UTF-8 codepoint of nn hex. >> >> 3) All valid ISO-8859-1 characters have a character code between 20 >> hex and 7E hex, or between A0 hex and FF hex. >> https://en.wikipedia.org/wiki/ISO/IEC_8859-1 >> >> 4) All valid ASCII characters have a character code between 00 hex and 7E hex. >> https://en.wikipedia.org/wiki/ASCII >> >> >> 5) a) All character codes which are defined within ISO-8859-1 and also >> defined within ASCII. (i.e. character codes 20 hex to 7E hex) are >> defined identically in both. >> >> b) All printable ASCII characters are defined identically in both >> ASCII and ISO-8859-1 >> >> 6) All character codes defined in ASCII (00 hex to 7E hex) are >> defined identically in Unicode UTF-8. >> >> 7) All character codes defined in ISO-8859-1 (20 hex - 7E hex ; A0 hex >> - FF hex ) are defined identically in UTF-8. >> >> 8) => some Unicode codepoints map to both ASCII and ISO-8859-1. >> all ASCII maps 1:1 to Unicode UTF-8 >> all ISO-8859-1 maps 1:1 to Unicode UTF-8 >> >> 9) All ByteStrings elements which are either a valid ISO-8859-1 >> character or a valid ASCII character are *also* a valid UTF-8 >> character. >> >> 10) ISO-8859-1 characters representing a character with a diacritic, >> or a two-character ligature, have no ASCII equivalent. In Unicode >> UTF-8, those character codes which are representing compound glyphs, >> are called "compatibility codepoints". >> >> 11) The preferred Unicode representation of the characters which have >> compatibility codepoints is as a a short set of codepoints >> representing the characters which are combined together to form the >> glyph of the convenience codepoint, as a sequence of bytes >> representing the component characters. >> >> >> 12) Some concrete examples: >> >> A - aka Upper Case A >> In ASCII, in ISO 8859-1 >> ASCII A - 41 hex >> ISO-8859-1 A - 41 hex >> UTF-8 A - 41 hex >> >> BEL (a bell sound, often invoked by a Ctrl-g keyboard chord) >> In ASCII, not in ISO 8859-1 >> ASCII : BEL - 07 hex >> ISO-8859-1 : 07 hex is not a valid character code >> UTF-8 : BEL - 07 hex >> >> £ (GBP currency symbol) >> In ISO-8859-1, not in ASCII >> ASCII : A3 hex is not a valid ASCII code >> UTF-8: £ - A3 hex >> ISO-8859-1: £ - A3 hex >> >> Upper Case C cedilla >> In ISO-8859-1, not in ASCII, in UTF-8 as a compatibility codepoint >> *and* a composed set of codepoints >> ASCII : C7 hex is not a valid ASCII character code >> ISO-8859-1 : Upper Case C cedilla - C7 hex >> UTF-8 : Upper Case C cedilla (compatibility codepoint) - C7 hex >> Unicode preferred Upper Case C cedilla (composed set of codepoints) >> Upper case C 0043 hex (Upper case C) >> followed by >> cedilla 00B8 hex (cedilla) >> >> 13) For any valid ASCII string *and* for any valid ISO-8859-1 string, >> aByteString is completely adequate for editing and display. >> >> 14) When sorting any valid ASCII string *or* any valid ISO-8859-1 >> string, upper and lower case versions of the same character will be >> treated differently. >> >> 15) When sorting any valid ISO-8859-1 string containing >> letter+diacritic combination glyphs or ligature combination glyphs, >> the glyphs in combination will treated differently to a "plain" glyph >> of the character >> i.e. "C" and "C cedilla" will be treated very differently. "ß" and >> "fs" will be treated very differently. >> >> 16) Different nations have different rules about where diacritic-ed >> characted and ligature pairs should be placed when in alphabetical >> order. >> >> 17) Some nations even have multiple standards - e.g. surnames >> beginning either "M superscript-c" or "M superscript-a superscript-c" >> are treated as beginning equivalently in UK phone directories, but not >> in other situations. >> >> >> Some practical upshots >> ================== >> >> 1) Cuis and its ISO-8859-1 encoding is *exactly* the same as UTF-8, >> for any single character it considers valid, or any ByteString it has >> made up of characters it considers valid. >> >> 2) Any ByteString is valid UTF-8 in any of Squeak, Pharo, Cuis or any >> other Smalltalk with a single byte ByteString following ASCII or >> ISO-8859-1. >> >> 3) Any Smalltalk (or derivative language) using ByteString can >> immediately consider it's ByteString as valid UTF-8, as long as it >> also considers the ByteSring as valid ASCII and/or ISO-8859-1. >> >> 4) All of those can be successfully exported to any system using UTF-8 >> (e.g. HTML). >> >> 5) To successfully *accept* all UTF-8 we much be able to do either: >> a) accept UTF-8 strings with composed characters >> b) convert UTF-8 strings with composed characters into UTF-8 strings >> that use *only* compatibility codepoints. >> >> >> Class + protocol proposals >> >> >> >> a Utf8CompatibilityString class. >> >> asByteString - ensure only compatibility codepoints are used. >> Ensure it doews not encode characters above 00FF hex. >> >> asIso8859String - ensures only compatibility codepoints are used, >> and that the characters are each valid ISO 8859-1 >> >> asAsciiString - ensures only characters 00hex - 7F hex are used. >> >> asUtf8ComposedIso8859String - ensures all compatibility codepoints >> are expanded into small OrderedCollections of codepoints >> >> a Utf8ComposedIso8859String class - will provide sortable and >> comparable UTF8 strings of all ASCII and ISO 8859-1 strings. >> >> Then a Utf8SortableCollection class - a collection of >> Utf8ComposedIso8859Strings words and phrases. >> >> Custom sortBlocks will define the applicable sort order. >> >> We can create a collection... a Dictionary, thinking about it, of >> named, prefabricated sortBlocks. >> >> This will work for all UTF8 strings of ISO-8859-1 and ASCII strings. >> >> If anyone has better names for the classes, please let me know. >> >> If anyone else wants to help >> - build these, >> - create SUnit tests for these >> - write documentation for these >> Please let me know. >> >> n.b. I have had absolutely no experience of Ropes. >> >> My own background with this stuff: In the early 90's as a Project >> Manager implementing office automation systems across a global >> company, with offices in the Americas, Western, Eastern and Central >> Europe, (including Slavic and Cyrillic users) nations, Japan and >> China. The mission-critical application was word-processing. >> >> Our offices were spread around the globe, and we needed those offices >> to successfully exchange documents with their sister offices, and with >> the customers in each region the offices were in. >> >> Unicode was then new, and our platform supplier was the NeXT >> Corporation, who had been founder members in of the Unicode Consortium >> in 1990. >> >> So far: I've read the latest version of the Unicode Standard (v8.0). >> This is freely downloadable. >> I've purchased a paper copy of an earlier release. New releases >> typically consist additional codespaces (i.e. alphabets). So old >> copies are useful, as well as cheap. (Paper copies of version 4.0 >> are available second-hand for < $10 / €10). >> >> The typical change with each release is the addition of further >> codespaces (i.e alphabets (more or less) ), so you don't lose a lot. >> (I'll be going through my V4.0 just to make sure) >> >> Cheers, >> Euan >> >> >> >> >> On 5 December 2015 at 13:08, stepharo <stepharo(a)free.fr> wrote: >>> Hi EuanM >>> >>> Le 4/12/15 12:42, EuanM a écrit : >>>> >>>> I'm currently groping my way to seeing how feature-complete our >>>> Unicode support is. I am doing this to establish what still needs to >>>> be done to provide full Unicode support. >>> >>> >>> this is great. Thanks for pushing this. I wrote and collected some roadmap >>> (analyses on different topics) >>> on the pharo github project feel free to add this one there. >>>> >>>> >>>> This seems to me to be an area where it would be best to write it >>>> once, and then have the same codebase incorporated into the Smalltalks >>>> that most share a common ancestry. >>>> >>>> I am keen to get: equality-testing for strings; sortability for >>>> strings which have ligatures and diacritic characters; and correct >>>> round-tripping of data. >>> >>> Go! >>> My suggestion is >>> start small >>> make steady progress >>> write tests >>> commit often :) >>> >>> Stef >>> >>> What is the french phoneBook ordering because this is the first time I hear >>> about it. >>> >>>> >>>> Call to action: >>>> ========== >>>> >>>> If you have comments on these proposals - such as "but we already have >>>> that facility" or "the reason we do not have these facilities is >>>> because they are dog-slow" - please let me know them. >>>> >>>> If you would like to help out, please let me know. >>>> >>>> If you have Unicode experience and expertise, and would like to be, or >>>> would be willing to be, in the 'council of experts' for this project, >>>> please let me know. >>>> >>>> If you have comments or ideas on anything mentioned in this email >>>> >>>> In the first instance, the initiative's website will be: >>>> http://smalltalk.uk.to/unicode.html >>>> >>>> I have created a SqueakSource.com project called UnicodeSupport >>>> >>>> I want to avoid re-inventing any facilities which already exist. >>>> Except where they prevent us reaching the goals of: >>>> - sortable UTF8 strings >>>> - sortable UTF16 strings >>>> - equivalence testing of 2 UTF8 strings >>>> - equivalence testing of 2 UTF16 strings >>>> - round-tripping UTF8 strings through Smalltalk >>>> - roundtripping UTF16 strings through Smalltalk. >>>> As I understand it, we have limited Unicode support atm. >>>> >>>> Current state of play >>>> =============== >>>> ByteString gets converted to WideString when need is automagically >>>> detected. >>>> >>>> Is there anything else that currently exists? >>>> >>>> Definition of Terms >>>> ============== >>>> A quick definition of terms before I go any further: >>>> >>>> Standard terms from the Unicode standard >>>> =============================== >>>> a compatibility character : an additional encoding of a *normal* >>>> character, for compatibility and round-trip conversion purposes. For >>>> instance, a 1-byte encoding of a Latin character with a diacritic. >>>> >>>> Made-up terms >>>> ============ >>>> a convenience codepoint : a single codepoint which represents an item >>>> that is also encoded as a string of codepoints. >>>> >>>> (I tend to use the terms compatibility character and compatibility >>>> codepoint interchangably. The standard only refers to them as >>>> compatibility characters. However, the standard is determined to >>>> emphasise that characters are abstract and that codepoints are >>>> concrete. So I think it is often more useful and productive to think >>>> of compatibility or convenience codepoints). >>>> >>>> a composed character : a character made up of several codepoints >>>> >>>> Unicode encoding explained >>>> ===================== >>>> A convenience codepoint can therefore be thought of as a code point >>>> used for a character which also has a composed form. >>>> >>>> The way Unicode works is that sometimes you can encode a character in >>>> one byte, sometimes not. Sometimes you can encode it in two bytes, >>>> sometimes not. >>>> >>>> You can therefore have a long stream of ASCII which is single-byte >>>> Unicode. If there is an occasional Cyrillic or Greek character in the >>>> stream, it would be represented either by a compatibility character or >>>> by a multi-byte combination. >>>> >>>> Using compatibility characters can prevent proper sorting and >>>> equivalence testing. >>>> >>>> Using "pure" Unicode, ie. "normal encodings", can cause compatibility >>>> and round-tripping probelms. Although avoiding them can *also* cause >>>> compatibility issues and round-tripping problems. >>>> >>>> Currently my thinking is: >>>> >>>> a Utf8String class >>>> an Ordered collection, with 1 byte characters as the modal element, >>>> but short arrays of wider strings where necessary >>>> a Utf16String class >>>> an Ordered collection, with 2 byte characters as the modal element, >>>> but short arrays of wider strings >>>> beginning with a 2-byte endianness indicator. >>>> >>>> Utf8Strings sometimes need to be sortable, and sometimes need to be >>>> compatible. >>>> >>>> So my thinking is that Utf8String will contain convenience codepoints, >>>> for round-tripping. And where there are multiple convenience >>>> codepoints for a character, that it standardises on one. >>>> >>>> And that there is a Utf8SortableString which uses *only* normal >>>> characters. >>>> >>>> We then need methods to convert between the two. >>>> >>>> aUtf8String asUtf8SortableString >>>> >>>> and >>>> >>>> aUtf8SortableString asUtf8String >>>> >>>> >>>> Sort orders are culture and context dependent - Sweden and Germany >>>> have different sort orders for the same diacritic-ed characters. Some >>>> countries have one order in general usage, and another for specific >>>> usages, such as phone directories (e.g. UK and France) >>>> >>>> Similarly for Utf16 : Utf16String and Utf16SortableString and >>>> conversion methods >>>> >>>> A list of sorted words would be a SortedCollection, and there could be >>>> pre-prepared sortBlocks for them, e.g. frPhoneBookOrder, deOrder, >>>> seOrder, ukOrder, etc >>>> >>>> along the lines of >>>> aListOfWords := SortedCollection sortBlock: deOrder >>>> >>>> If a word is either a Utf8SortableString, or a well-formed Utf8String, >>>> then we can perform equivalence testing on them trivially. >>>> >>>> To make sure a Utf8String is well formed, we would need to have a way >>>> of cleaning up any convenience codepoints which were valid, but which >>>> were for a character which has multiple equally-valid alternative >>>> convenience codepoints, and for which the string currently had the >>>> "wrong" convenience codepoint. (i.e for any character with valid >>>> alternative convenience codepoints, we would choose one to be in the >>>> well-formed Utf8String, and we would need a method for cleaning the >>>> alternative convenience codepoints out of the string, and replacing >>>> them with the chosen approved convenience codepoint. >>>> >>>> aUtf8String cleanUtf8String >>>> >>>> With WideString, a lot of the issues disappear - except >>>> round-tripping(although I'm sure I have seen something recently about >>>> 4-byte strings that also have an additional bit. Which would make >>>> some Unicode characters 5-bytes long.) >>>> >>>> >>>> (I'm starting to zone out now - if I've overlooked anything - obvious, >>>> subtle, or somewhere in between, please let me know) >>>> >>>> Cheers, >>>> Euan >>>> >>>> >>> >>> > >> On 07 Dec 2015, at 04:21, EuanM <euanmee(a)gmail.com> wrote: >> >> This a long email. A *lot* of it is encapsulated in the Venn diagram both: >> http://smalltalk.uk.to/unicode-utf8.html >> and my Smalltalk in Small Steps blog at: >> http://smalltalkinsmallsteps.blogspot.co.uk/2015/12/utf-8-for-cuis-pharo-an… >> >> My current thinking, and understanding. >> ============================== >> >> 0) a) ASCII and ISO-8859-1 consist of characters encoded in 1 byte. >> b) UTF-8 can encode all of those characters in 1 byte, but can >> prefer some of them to be encoded as sequences of multiple bytes. And >> can encode additional characters as sequences of multiple bytes. >> >> 1) Smalltalk has long had multiple String classes. >> >> 2) Any UTF16 Unicode codepoint which has a codepoint of 00nn hex >> is encoded as a UTF-8 codepoint of nn hex. >> >> 3) All valid ISO-8859-1 characters have a character code between 20 >> hex and 7E hex, or between A0 hex and FF hex. >> https://en.wikipedia.org/wiki/ISO/IEC_8859-1 >> >> 4) All valid ASCII characters have a character code between 00 hex and 7E hex. >> https://en.wikipedia.org/wiki/ASCII >> >> >> 5) a) All character codes which are defined within ISO-8859-1 and also >> defined within ASCII. (i.e. character codes 20 hex to 7E hex) are >> defined identically in both. >> >> b) All printable ASCII characters are defined identically in both >> ASCII and ISO-8859-1 >> >> 6) All character codes defined in ASCII (00 hex to 7E hex) are >> defined identically in Unicode UTF-8. >> >> 7) All character codes defined in ISO-8859-1 (20 hex - 7E hex ; A0 hex >> - FF hex ) are defined identically in UTF-8. >> >> 8) => some Unicode codepoints map to both ASCII and ISO-8859-1. >> all ASCII maps 1:1 to Unicode UTF-8 >> all ISO-8859-1 maps 1:1 to Unicode UTF-8 >> >> 9) All ByteStrings elements which are either a valid ISO-8859-1 >> character or a valid ASCII character are *also* a valid UTF-8 >> character. >> >> 10) ISO-8859-1 characters representing a character with a diacritic, >> or a two-character ligature, have no ASCII equivalent. In Unicode >> UTF-8, those character codes which are representing compound glyphs, >> are called "compatibility codepoints". >> >> 11) The preferred Unicode representation of the characters which have >> compatibility codepoints is as a a short set of codepoints >> representing the characters which are combined together to form the >> glyph of the convenience codepoint, as a sequence of bytes >> representing the component characters. >> >> >> 12) Some concrete examples: >> >> A - aka Upper Case A >> In ASCII, in ISO 8859-1 >> ASCII A - 41 hex >> ISO-8859-1 A - 41 hex >> UTF-8 A - 41 hex >> >> BEL (a bell sound, often invoked by a Ctrl-g keyboard chord) >> In ASCII, not in ISO 8859-1 >> ASCII : BEL - 07 hex >> ISO-8859-1 : 07 hex is not a valid character code >> UTF-8 : BEL - 07 hex >> >> £ (GBP currency symbol) >> In ISO-8859-1, not in ASCII >> ASCII : A3 hex is not a valid ASCII code >> UTF-8: £ - A3 hex >> ISO-8859-1: £ - A3 hex >> >> Upper Case C cedilla >> In ISO-8859-1, not in ASCII, in UTF-8 as a compatibility codepoint >> *and* a composed set of codepoints >> ASCII : C7 hex is not a valid ASCII character code >> ISO-8859-1 : Upper Case C cedilla - C7 hex >> UTF-8 : Upper Case C cedilla (compatibility codepoint) - C7 hex >> Unicode preferred Upper Case C cedilla (composed set of codepoints) >> Upper case C 0043 hex (Upper case C) >> followed by >> cedilla 00B8 hex (cedilla) >> >> 13) For any valid ASCII string *and* for any valid ISO-8859-1 string, >> aByteString is completely adequate for editing and display. >> >> 14) When sorting any valid ASCII string *or* any valid ISO-8859-1 >> string, upper and lower case versions of the same character will be >> treated differently. >> >> 15) When sorting any valid ISO-8859-1 string containing >> letter+diacritic combination glyphs or ligature combination glyphs, >> the glyphs in combination will treated differently to a "plain" glyph >> of the character >> i.e. "C" and "C cedilla" will be treated very differently. "ß" and >> "fs" will be treated very differently. >> >> 16) Different nations have different rules about where diacritic-ed >> characted and ligature pairs should be placed when in alphabetical >> order. >> >> 17) Some nations even have multiple standards - e.g. surnames >> beginning either "M superscript-c" or "M superscript-a superscript-c" >> are treated as beginning equivalently in UK phone directories, but not >> in other situations. >> >> >> Some practical upshots >> ================== >> >> 1) Cuis and its ISO-8859-1 encoding is *exactly* the same as UTF-8, >> for any single character it considers valid, or any ByteString it has >> made up of characters it considers valid. >> >> 2) Any ByteString is valid UTF-8 in any of Squeak, Pharo, Cuis or any >> other Smalltalk with a single byte ByteString following ASCII or >> ISO-8859-1. >> >> 3) Any Smalltalk (or derivative language) using ByteString can >> immediately consider it's ByteString as valid UTF-8, as long as it >> also considers the ByteSring as valid ASCII and/or ISO-8859-1. >> >> 4) All of those can be successfully exported to any system using UTF-8 >> (e.g. HTML). >> >> 5) To successfully *accept* all UTF-8 we much be able to do either: >> a) accept UTF-8 strings with composed characters >> b) convert UTF-8 strings with composed characters into UTF-8 strings >> that use *only* compatibility codepoints. >> >> >> Class + protocol proposals >> >> >> >> a Utf8CompatibilityString class. >> >> asByteString - ensure only compatibility codepoints are used. >> Ensure it doews not encode characters above 00FF hex. >> >> asIso8859String - ensures only compatibility codepoints are used, >> and that the characters are each valid ISO 8859-1 >> >> asAsciiString - ensures only characters 00hex - 7F hex are used. >> >> asUtf8ComposedIso8859String - ensures all compatibility codepoints >> are expanded into small OrderedCollections of codepoints >> >> a Utf8ComposedIso8859String class - will provide sortable and >> comparable UTF8 strings of all ASCII and ISO 8859-1 strings. >> >> Then a Utf8SortableCollection class - a collection of >> Utf8ComposedIso8859Strings words and phrases. >> >> Custom sortBlocks will define the applicable sort order. >> >> We can create a collection... a Dictionary, thinking about it, of >> named, prefabricated sortBlocks. >> >> This will work for all UTF8 strings of ISO-8859-1 and ASCII strings. >> >> If anyone has better names for the classes, please let me know. >> >> If anyone else wants to help >> - build these, >> - create SUnit tests for these >> - write documentation for these >> Please let me know. >> >> n.b. I have had absolutely no experience of Ropes. >> >> My own background with this stuff: In the early 90's as a Project >> Manager implementing office automation systems across a global >> company, with offices in the Americas, Western, Eastern and Central >> Europe, (including Slavic and Cyrillic users) nations, Japan and >> China. The mission-critical application was word-processing. >> >> Our offices were spread around the globe, and we needed those offices >> to successfully exchange documents with their sister offices, and with >> the customers in each region the offices were in. >> >> Unicode was then new, and our platform supplier was the NeXT >> Corporation, who had been founder members in of the Unicode Consortium >> in 1990. >> >> So far: I've read the latest version of the Unicode Standard (v8.0). >> This is freely downloadable. >> I've purchased a paper copy of an earlier release. New releases >> typically consist additional codespaces (i.e. alphabets). So old >> copies are useful, as well as cheap. (Paper copies of version 4.0 >> are available second-hand for < $10 / €10). >> >> The typical change with each release is the addition of further >> codespaces (i.e alphabets (more or less) ), so you don't lose a lot. >> (I'll be going through my V4.0 just to make sure) >> >> Cheers, >> Euan >> >> >> >> >> On 5 December 2015 at 13:08, stepharo <stepharo(a)free.fr> wrote: >>> Hi EuanM >>> >>> Le 4/12/15 12:42, EuanM a écrit : >>>> >>>> I'm currently groping my way to seeing how feature-complete our >>>> Unicode support is. I am doing this to establish what still needs to >>>> be done to provide full Unicode support. >>> >>> >>> this is great. Thanks for pushing this. I wrote and collected some roadmap >>> (analyses on different topics) >>> on the pharo github project feel free to add this one there. >>>> >>>> >>>> This seems to me to be an area where it would be best to write it >>>> once, and then have the same codebase incorporated into the Smalltalks >>>> that most share a common ancestry. >>>> >>>> I am keen to get: equality-testing for strings; sortability for >>>> strings which have ligatures and diacritic characters; and correct >>>> round-tripping of data. >>> >>> Go! >>> My suggestion is >>> start small >>> make steady progress >>> write tests >>> commit often :) >>> >>> Stef >>> >>> What is the french phoneBook ordering because this is the first time I hear >>> about it. >>> >>>> >>>> Call to action: >>>> ========== >>>> >>>> If you have comments on these proposals - such as "but we already have >>>> that facility" or "the reason we do not have these facilities is >>>> because they are dog-slow" - please let me know them. >>>> >>>> If you would like to help out, please let me know. >>>> >>>> If you have Unicode experience and expertise, and would like to be, or >>>> would be willing to be, in the 'council of experts' for this project, >>>> please let me know. >>>> >>>> If you have comments or ideas on anything mentioned in this email >>>> >>>> In the first instance, the initiative's website will be: >>>> http://smalltalk.uk.to/unicode.html >>>> >>>> I have created a SqueakSource.com project called UnicodeSupport >>>> >>>> I want to avoid re-inventing any facilities which already exist. >>>> Except where they prevent us reaching the goals of: >>>> - sortable UTF8 strings >>>> - sortable UTF16 strings >>>> - equivalence testing of 2 UTF8 strings >>>> - equivalence testing of 2 UTF16 strings >>>> - round-tripping UTF8 strings through Smalltalk >>>> - roundtripping UTF16 strings through Smalltalk. >>>> As I understand it, we have limited Unicode support atm. >>>> >>>> Current state of play >>>> =============== >>>> ByteString gets converted to WideString when need is automagically >>>> detected. >>>> >>>> Is there anything else that currently exists? >>>> >>>> Definition of Terms >>>> ============== >>>> A quick definition of terms before I go any further: >>>> >>>> Standard terms from the Unicode standard >>>> =============================== >>>> a compatibility character : an additional encoding of a *normal* >>>> character, for compatibility and round-trip conversion purposes. For >>>> instance, a 1-byte encoding of a Latin character with a diacritic. >>>> >>>> Made-up terms >>>> ============ >>>> a convenience codepoint : a single codepoint which represents an item >>>> that is also encoded as a string of codepoints. >>>> >>>> (I tend to use the terms compatibility character and compatibility >>>> codepoint interchangably. The standard only refers to them as >>>> compatibility characters. However, the standard is determined to >>>> emphasise that characters are abstract and that codepoints are >>>> concrete. So I think it is often more useful and productive to think >>>> of compatibility or convenience codepoints). >>>> >>>> a composed character : a character made up of several codepoints >>>> >>>> Unicode encoding explained >>>> ===================== >>>> A convenience codepoint can therefore be thought of as a code point >>>> used for a character which also has a composed form. >>>> >>>> The way Unicode works is that sometimes you can encode a character in >>>> one byte, sometimes not. Sometimes you can encode it in two bytes, >>>> sometimes not. >>>> >>>> You can therefore have a long stream of ASCII which is single-byte >>>> Unicode. If there is an occasional Cyrillic or Greek character in the >>>> stream, it would be represented either by a compatibility character or >>>> by a multi-byte combination. >>>> >>>> Using compatibility characters can prevent proper sorting and >>>> equivalence testing. >>>> >>>> Using "pure" Unicode, ie. "normal encodings", can cause compatibility >>>> and round-tripping probelms. Although avoiding them can *also* cause >>>> compatibility issues and round-tripping problems. >>>> >>>> Currently my thinking is: >>>> >>>> a Utf8String class >>>> an Ordered collection, with 1 byte characters as the modal element, >>>> but short arrays of wider strings where necessary >>>> a Utf16String class >>>> an Ordered collection, with 2 byte characters as the modal element, >>>> but short arrays of wider strings >>>> beginning with a 2-byte endianness indicator. >>>> >>>> Utf8Strings sometimes need to be sortable, and sometimes need to be >>>> compatible. >>>> >>>> So my thinking is that Utf8String will contain convenience codepoints, >>>> for round-tripping. And where there are multiple convenience >>>> codepoints for a character, that it standardises on one. >>>> >>>> And that there is a Utf8SortableString which uses *only* normal >>>> characters. >>>> >>>> We then need methods to convert between the two. >>>> >>>> aUtf8String asUtf8SortableString >>>> >>>> and >>>> >>>> aUtf8SortableString asUtf8String >>>> >>>> >>>> Sort orders are culture and context dependent - Sweden and Germany >>>> have different sort orders for the same diacritic-ed characters. Some >>>> countries have one order in general usage, and another for specific >>>> usages, such as phone directories (e.g. UK and France) >>>> >>>> Similarly for Utf16 : Utf16String and Utf16SortableString and >>>> conversion methods >>>> >>>> A list of sorted words would be a SortedCollection, and there could be >>>> pre-prepared sortBlocks for them, e.g. frPhoneBookOrder, deOrder, >>>> seOrder, ukOrder, etc >>>> >>>> along the lines of >>>> aListOfWords := SortedCollection sortBlock: deOrder >>>> >>>> If a word is either a Utf8SortableString, or a well-formed Utf8String, >>>> then we can perform equivalence testing on them trivially. >>>> >>>> To make sure a Utf8String is well formed, we would need to have a way >>>> of cleaning up any convenience codepoints which were valid, but which >>>> were for a character which has multiple equally-valid alternative >>>> convenience codepoints, and for which the string currently had the >>>> "wrong" convenience codepoint. (i.e for any character with valid >>>> alternative convenience codepoints, we would choose one to be in the >>>> well-formed Utf8String, and we would need a method for cleaning the >>>> alternative convenience codepoints out of the string, and replacing >>>> them with the chosen approved convenience codepoint. >>>> >>>> aUtf8String cleanUtf8String >>>> >>>> With WideString, a lot of the issues disappear - except >>>> round-tripping(although I'm sure I have seen something recently about >>>> 4-byte strings that also have an additional bit. Which would make >>>> some Unicode characters 5-bytes long.) >>>> >>>> >>>> (I'm starting to zone out now - if I've overlooked anything - obvious, >>>> subtle, or somewhere in between, please let me know) >>>> >>>> Cheers, >>>> Euan >>>> >>>> >>> >>> >> > >

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Re: [Pharo-dev] Unicode Support
by EuanM 07 Dec '15

07 Dec '15

"Canonicalisation and sorting issues are hardly discussed. In one place, the fact that a lot of special characters can have multiple representations is a big argument, while it is not mentioned how just treating things like a byte sequence would solve this (it doesn't AFAIU). Like how do you search for $e or $é if you know that it is possible to represent $é as just $é and as $e + $´ ?" This, for me, is one of the chief purposes of Unicode support. What you have it a convertor for "might contain compatibility codepoints" to "contains only composed sequences of codepoints, and no compatibility codepoints". As long as you're not using Strings where you should use Streams, it should be okay. And of course, for passing back to ISO Latin 1 or ASCII systems, you need to have a convertor to "contains only compatibility codepoints, and no composed sets of codepoints". As long as you can tell one type from the other, it's not a problem. Any string that mixes both can be converted in either direction by the same methods which I've just outlined. Once you have these, we can do this for all 1 byte characters. We can then expand this to have Classes and methods for character strings which contain the occasional character from other ISO character sets. Cheers, Euan On 6 December 2015 at 17:44, Sven Van Caekenberghe <sven(a)stfx.eu> wrote: > >> On 05 Dec 2015, at 17:35, Todd Blanchard <tblanchard(a)mac.com> wrote: >> >> would suggest that the only worthwhile encoding is UTF8 - the rest are distractions except for being able to read and convert from other encodings to UTF8. UTF16 is a complete waste of time. >> >> Read http://utf8everywhere.org/ >> >> I have extensive Unicode chops from around 1999 to 2004 and my experience leads me to strongly agree with the views on that site. > > Well, I read the page/document/site as well. It was very interesting indeed, thanks for sharing it. > > In some sense it made me reconsider my aversion against in-image utf-8 encoding, maybe it could have some value. Absolute storage is more efficient, some processing might also be more efficient, i/o conversions to/from utf-8 become a no-op. What I found nice is the suggestion that most structured parsing (XML, JSON, CSV, STON, ...) could actually ignore the encoding for a large part and just assume its ASCII, which would/could be nice for performance. Also the fact that a lot of strings are (or should be) treated as opaque makes a lot of sense. > > What I did not like is that much of argumentation is based on issue in the Windows world, take all that away and the document shrinks in half. I would have liked a bit more fundamental CS arguments. > > Canonicalisation and sorting issues are hardly discussed. > > In one place, the fact that a lot of special characters can have multiple representations is a big argument, while it is not mentioned how just treating things like a byte sequence would solve this (it doesn't AFAIU). Like how do you search for $e or $é if you know that it is possible to represent $é as just $é and as $e + $´ ? > > Sven > >> Sent from the road >> >> On Dec 5, 2015, at 05:08, stepharo <stepharo(a)free.fr> wrote: >> >>> Hi EuanM >>> >>> Le 4/12/15 12:42, EuanM a écrit : >>>> I'm currently groping my way to seeing how feature-complete our >>>> Unicode support is. I am doing this to establish what still needs to >>>> be done to provide full Unicode support. >>> >>> this is great. Thanks for pushing this. I wrote and collected some roadmap (analyses on different topics) >>> on the pharo github project feel free to add this one there. >>>> >>>> This seems to me to be an area where it would be best to write it >>>> once, and then have the same codebase incorporated into the Smalltalks >>>> that most share a common ancestry. >>>> >>>> I am keen to get: equality-testing for strings; sortability for >>>> strings which have ligatures and diacritic characters; and correct >>>> round-tripping of data. >>> Go! >>> My suggestion is >>> start small >>> make steady progress >>> write tests >>> commit often :) >>> >>> Stef >>> >>> What is the french phoneBook ordering because this is the first time I hear about it. >>>> >>>> Call to action: >>>> ========== >>>> >>>> If you have comments on these proposals - such as "but we already have >>>> that facility" or "the reason we do not have these facilities is >>>> because they are dog-slow" - please let me know them. >>>> >>>> If you would like to help out, please let me know. >>>> >>>> If you have Unicode experience and expertise, and would like to be, or >>>> would be willing to be, in the 'council of experts' for this project, >>>> please let me know. >>>> >>>> If you have comments or ideas on anything mentioned in this email >>>> >>>> In the first instance, the initiative's website will be: >>>> http://smalltalk.uk.to/unicode.html >>>> >>>> I have created a SqueakSource.com project called UnicodeSupport >>>> >>>> I want to avoid re-inventing any facilities which already exist. >>>> Except where they prevent us reaching the goals of: >>>> - sortable UTF8 strings >>>> - sortable UTF16 strings >>>> - equivalence testing of 2 UTF8 strings >>>> - equivalence testing of 2 UTF16 strings >>>> - round-tripping UTF8 strings through Smalltalk >>>> - roundtripping UTF16 strings through Smalltalk. >>>> As I understand it, we have limited Unicode support atm. >>>> >>>> Current state of play >>>> =============== >>>> ByteString gets converted to WideString when need is automagically detected. >>>> >>>> Is there anything else that currently exists? >>>> >>>> Definition of Terms >>>> ============== >>>> A quick definition of terms before I go any further: >>>> >>>> Standard terms from the Unicode standard >>>> =============================== >>>> a compatibility character : an additional encoding of a *normal* >>>> character, for compatibility and round-trip conversion purposes. For >>>> instance, a 1-byte encoding of a Latin character with a diacritic. >>>> >>>> Made-up terms >>>> ============ >>>> a convenience codepoint : a single codepoint which represents an item >>>> that is also encoded as a string of codepoints. >>>> >>>> (I tend to use the terms compatibility character and compatibility >>>> codepoint interchangably. The standard only refers to them as >>>> compatibility characters. However, the standard is determined to >>>> emphasise that characters are abstract and that codepoints are >>>> concrete. So I think it is often more useful and productive to think >>>> of compatibility or convenience codepoints). >>>> >>>> a composed character : a character made up of several codepoints >>>> >>>> Unicode encoding explained >>>> ===================== >>>> A convenience codepoint can therefore be thought of as a code point >>>> used for a character which also has a composed form. >>>> >>>> The way Unicode works is that sometimes you can encode a character in >>>> one byte, sometimes not. Sometimes you can encode it in two bytes, >>>> sometimes not. >>>> >>>> You can therefore have a long stream of ASCII which is single-byte >>>> Unicode. If there is an occasional Cyrillic or Greek character in the >>>> stream, it would be represented either by a compatibility character or >>>> by a multi-byte combination. >>>> >>>> Using compatibility characters can prevent proper sorting and >>>> equivalence testing. >>>> >>>> Using "pure" Unicode, ie. "normal encodings", can cause compatibility >>>> and round-tripping probelms. Although avoiding them can *also* cause >>>> compatibility issues and round-tripping problems. >>>> >>>> Currently my thinking is: >>>> >>>> a Utf8String class >>>> an Ordered collection, with 1 byte characters as the modal element, >>>> but short arrays of wider strings where necessary >>>> a Utf16String class >>>> an Ordered collection, with 2 byte characters as the modal element, >>>> but short arrays of wider strings >>>> beginning with a 2-byte endianness indicator. >>>> >>>> Utf8Strings sometimes need to be sortable, and sometimes need to be compatible. >>>> >>>> So my thinking is that Utf8String will contain convenience codepoints, >>>> for round-tripping. And where there are multiple convenience >>>> codepoints for a character, that it standardises on one. >>>> >>>> And that there is a Utf8SortableString which uses *only* normal characters. >>>> >>>> We then need methods to convert between the two. >>>> >>>> aUtf8String asUtf8SortableString >>>> >>>> and >>>> >>>> aUtf8SortableString asUtf8String >>>> >>>> >>>> Sort orders are culture and context dependent - Sweden and Germany >>>> have different sort orders for the same diacritic-ed characters. Some >>>> countries have one order in general usage, and another for specific >>>> usages, such as phone directories (e.g. UK and France) >>>> >>>> Similarly for Utf16 : Utf16String and Utf16SortableString and >>>> conversion methods >>>> >>>> A list of sorted words would be a SortedCollection, and there could be >>>> pre-prepared sortBlocks for them, e.g. frPhoneBookOrder, deOrder, >>>> seOrder, ukOrder, etc >>>> >>>> along the lines of >>>> aListOfWords := SortedCollection sortBlock: deOrder >>>> >>>> If a word is either a Utf8SortableString, or a well-formed Utf8String, >>>> then we can perform equivalence testing on them trivially. >>>> >>>> To make sure a Utf8String is well formed, we would need to have a way >>>> of cleaning up any convenience codepoints which were valid, but which >>>> were for a character which has multiple equally-valid alternative >>>> convenience codepoints, and for which the string currently had the >>>> "wrong" convenience codepoint. (i.e for any character with valid >>>> alternative convenience codepoints, we would choose one to be in the >>>> well-formed Utf8String, and we would need a method for cleaning the >>>> alternative convenience codepoints out of the string, and replacing >>>> them with the chosen approved convenience codepoint. >>>> >>>> aUtf8String cleanUtf8String >>>> >>>> With WideString, a lot of the issues disappear - except >>>> round-tripping(although I'm sure I have seen something recently about >>>> 4-byte strings that also have an additional bit. Which would make >>>> some Unicode characters 5-bytes long.) >>>> >>>> >>>> (I'm starting to zone out now - if I've overlooked anything - obvious, >>>> subtle, or somewhere in between, please let me know) >>>> >>>> Cheers, >>>> Euan >>>> >>>> >>> >>> > >

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Daily Commit Log
by commits＠source.squeak.org 06 Dec '15

06 Dec '15

Changes to Trunk (http://source.squeak.org/trunk.html) in the last 24 hours: http://lists.squeakfoundation.org/pipermail/packages/2015-December/009209.h… Name: Tools-eem.658 Ancestors: Tools-eem.657 Fix the mssageList one-element-selection regression in Tools-eem.657. =============================================

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The Trunk: Tools-eem.658.mcz
by commits＠source.squeak.org 06 Dec '15

06 Dec '15

Eliot Miranda uploaded a new version of Tools to project The Trunk: http://source.squeak.org/trunk/Tools-eem.658.mcz ==================== Summary ==================== Name: Tools-eem.658 Author: eem Time: 6 December 2015, 12:20:40.433 pm UUID: 67c801aa-b3d5-4dc7-a52f-c49bbc7e0022 Ancestors: Tools-eem.657 Fix the mssageList one-element-selection regression in Tools-eem.657. =============== Diff against Tools-eem.657 =============== Item was changed: ----- Method: MessageNames>>selectorListIndex: (in category 'selector list') ----- selectorListIndex: anInteger "Set the selectorListIndex as specified, and propagate consequences" | methodClass index | methodClass := currentCompiledMethod ifNotNil: [currentCompiledMethod methodClass]. selectorListIndex := anInteger. self changed: #selectorListIndex. messageList := self computeMessageList. self changed: #messageList. + messageList size > 1 ifTrue: + [methodClass ifNotNil: [index := messageList findFirst: [:methodRef| methodRef actualClass = methodClass]]]. - methodClass ifNotNil: [index := messageList findFirst: [:methodRef| methodRef actualClass = methodClass]]. "If a method of the same class exists, select that, otherwise select the first message if any." self messageListIndex: (index ifNil: [1 min: messageList size])!

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